Solving Paradigms Brute Force Iterative Brute Force CF - 31A Worms Evolution very easy UVa - 10041 Vito's Family easy UVa - 102 easy Ecological Bin Packing 3 nested loops UVa - 10487 Closest Sums easy 2 nested loops CF - 106B easy 2 nested loops UVa - 10365 Blocks easy 2 nested loops CF - 7A Choosing Laptop Kalevitch and Chess easy UVa - 386 Perfect Cubes easy 3 nested loops UVa - 11621 Small Factors easy 2 nested loops UVa - 617 Nonstop Travel easy 2 nested loops UVa - 154 Recycling easy 3 nested loops, input parsing UVa - 703 Triple Ties: The Organizer's Nightmare easy 3 nested loops, sortings UVa - 10483 The Sum Equals the Product easy 3 nested loops, pruning UVa - 435 Block Voting 7.0 easy 2 nested loops, bitmasks UVa - 10662 The Wedding easy 3 nested loops UVa - 11205 The broken pedometer easy 2 nested loops, bitmasks UVa - 11342 Three-square easy 3 nested loops, preprocessing UVa - 1237 Expert Enough? easy UVa - 1260 Sales easy UVa - 735 Dart-a-Mania easy CF - 25A IQ test easy CF - 231A Team easy CF - 214A System of Equations easy CF - 520A Pangram easy CF - 189A Cut Ribbon easy UVa - 725 Division easy UVa - 441 Lotto easy solution without doubles specialists UVa - 11565 Simple Equations easy UVa - 11742 Social Constraints easy UVa - 12455 Bars easy UVa - 256 Quirksome Squares easy CF - 443B Kolya and Tandem Repeat easy CF - 316E1 Summer Homework easy CF - 18C Stripe easy CF - 698A Bets easy CF - 94B Friends easy CF - 38B Chess easy CF - 30A Accounting easy CF - 29A Spit Problem easy CF - 32A Reconnaissance easy CF - 88A Chord easy CF - 38C Blinds easy CF - 53A Autocomplete easy UVa - 443 Humble Numbers easy generator UVa - 640 Self Numbers easy generator, pruning CF - 977B Two-gram easy linear CF - 908B New Year and Buggy Bot easy grids, simulation CF - 58C Trees O(1) solution exists specialists seenX medium specialists UVa - 11959 Dice medium CF - 653C Bear and Up-Down medium 3 nested loops, dices CF - 63C Bulls and Cows medium CF - 300B Coach medium UVa - 305 Joseph medium hardcoding, Josephus problem variant CF - 231C To Add or Not to Add medium sortings CF - 1175C Electrification medium greedy specialists UVa - 11548 Blackboard Bonanza hard 4 nested loops UVa - 11464 Even Parity hard plus greedy, bitmasks UVa - 10309 Turn the Lights Off hard plus greedy important 11.0 important, first row brute force and rest follows specialists important, first row brute force and rest follows Recursive Brute Force (Backtracking) UVa - 524 Prime Ring Problem easy UVa - 167 The Sultan's Successors easy UVa - 624 CD easy pupils pupils pupils UVa - 10360 Rat Attack easy backward attack pupils UVa - 12346 Water Gate Management easy knapsack pupils UVa - 12249 Overlapping Scenes easy permutation UVa - 487 easy pruning, treemaps, comparator UVa - 10475 Help the Leaders easy treemaps, sortings UVa - 11515 Cranes easy bitmasks, geometry UVa - 131 The Psychic Poker Player easy cards, bitmasks UVa - 234 Switching Channels easy permutation UVa - 639 Don't Get Rooked easy boards UVa - 296 Safebreaker easy CF - 121A Lucky Sum easy CF - 371C Hamburgers easy UVa - 729 The Hamming Distance Problem Boggle Blitz max suffix matching prefix specialists filtered nice: for larger N, solvable with bipartite matching lucky numbers generation solvable with binary search easy 2.0 UVa - 10344 23 out of 5 easy 2.0 CF - 80C Heroes easy CF - 55B Smallest number CF - 114B PFAST Inc. CF - 96B Lucky Numbers (easy) medium UVa - 1251 Repeated Substitution with Sed medium easy easy bitmasks pupils UVa - 11201 The problem of the crazy linguist medium preprocessing pupils UVa - 1064 medium permutation, simulation pupils Network UVa - 12515 Movie Police medium UVa - 750 medium 8 Queens Chess Problem pupils hard compact graph, bitmasks UVa - 989 hard pruning UVa - 10957 So Doku Checker hard pruning UVa - 165 Stamps solvable with bfs, complexity analysis: factorial not exponential pupils UVa - 11065 A Gentlemen's Agreement Sudoko tedious implementation hard plus DP UVa - 10890 Maze hard pruning UVa - 10950 Bad Code hard UVa - 10582 ASCII Labyrinth hard count, input parsing, pruning Week test cases. My solution TLEs in worst case CF - 68C hard pruning GYM - 100863 Exhibition (E) Hall hard pruning, geometry CF - 285D Synchrophasotron hard pruning, hardcoding easy bfs, sieve specialists Permutation Sum complementary recursive functions, difficulty in proving complexity, solvable with DP proof ans = 0 for even n meet-in-the-middle solution State-Space Search UVa - 12101 Prime Path UVa - 652 Eight medium preprocessing, bfs, backward attack, grids, permutations specialists UVa - 321 The New Villa medium bfs, bitmasks specialists UVa - 1253 Infected Land hard bfs, grids specialists Greedy CF - 1003A Polycarp's Pockets very easy CF - 1148A Another One Bites The Dust very easy CF - 597B Restaurant easy classical problem CF - 261A Maxim and Discounts easy sortings UVa - 11520 Fill the Square easy grids CF - 159B Matchmaker easy two pointers CF - 154A Hometask easy CF - 701A Cards easy UVa - 10057 A mid-summer night's dream. easy median UVa - 11240 Antimonotonicity easy sequences, permutations UVa - 11824 A Minimum Land Price easy sortings UVa - 11532 Simple Adjacency Maximization easy bit manipulation UVa - 11039 Building designing easy sortings, two pointers CF - 65B easy Harry Potter and the History of Magic UVa - 11054 Wine trading in Gergovia easy UVa - 11389 The Bus Driver Problem easy CF - 3B pupils 7.0 registeration specialists balabizoo^3 solvable with DP has O(n * log maxDate) solution in case that dates can reach 1e9 10.2 Lorry easy sortings UVa - 11292 Dragon of Loowater easy sortings, two pointers CF - 673B Problems for Round easy CF - 26B Regular Bracket Sequence easy bracket matching UVa - 673 Parentheses Balance easy bracket matching UVa - 11111 Generalized Matrioshkas easy bracket matching UVa - 551 Nesting a Bunch of Brackets easy bracket matching CF - 350C Bombs easy sortings, manhattan distance CF - 33A What is for dinner? easy CF - 27C Unordered Subsequence easy CF - 17B Hierarchy easy SPOJ - AMR10G Christmas Play easy CF - 205B Little Elephant and Sorting easy CF - 376B I.O.U. easy CF - 215D Hot Days easy CF - 413C Jeopardy! easy sortings CF - 22D Segments easy intervals CF - 769B News About Credit easy sortings CF - 777B Game of Credit Cards easy sortings CF - 1176B Merge it! nice specialists sortings seenX pupils easy UVa - 10440 Ferry Loading II medium CF - 250C Movie Critics medium CF - 354A Vasya and Robot medium UVa -1605 backward attack, simulation cumulative sum, brute force Building for UN medium UVa - 10382 Watering Grass medium interval covering UVa - 410 Station Balance medium load balancing CF - 253C Text Editor medium CF - 67A Partial Teacher medium CF - 93B End of Exams medium CF - 95B Lucky Numbers medium CF - 58D Calendar medium CF - 515D Drazil and Tiles medium CF - 427E Police Patrol medium CF - 723C Polycarp at the Radio medium CF - 313C Ilya and Matrix medium CF - 219C Color Stripe medium CF - 754D Fedor and coupons medium intervals CF - 137C History medium intervals CF - 291D Parallel Programming medium CF - 223A Bracket Sequence medium bracket matching CF 746E Numbers Exchange medium sets CF - 257D Sum medium math needs careful double handling sortings, comparator, strings m > 1 is equivalent to the well-known problem m = 1 (see comments in editorial) sortings solution pattern: split into segments important, new idea in printing the solution specialists GYM - 100016D Group Stage medium GYM - 100247IMeteor Flow medium priorityqueues CF - 863E Turn Off The TV medium bracketing & events CF - 557C Arthur and Table medium sortings CSA Gerrymandering medium CF - 773C Prairie Partition medium CF - 1148D Dirty Deeds Done Dirt Cheap medium CF - 533E Correcting Mistakes hard CF - 89A Robbery hard CF - 496E Distributing Parts hard sortings, sets, intervals CF - 226B Naughty Stone Piles hard sortings, preprocessing ↗ nice editorial solution with binary search sortings solvable with dp or hashing experts Binary Search UVa - 10611 The Playboy Chimp very easy pupils UVa - 12032 The Monkey and the Oiled Bamboo easy UVa - 11428 Cubes easy two pointers UVa - 10566 Crossed Ladders easy bisection method CF - 702C Cellular Network easy two pointers UVa - 1079 A Careful Approach easy brute force, greedy UVa - 714 Copying Books easy greedy CF - 79B Colorful Field easy CF - 567D One-Dimensional Battle Ships UVa - 10170 The Hotel with Infinite Rooms CF - 68B Energy exchange composite easy easy medium UVa - 10341 Solve it medium UVa - 12192 Grapevine medium UVa - 10372 Leaps Tall Buildings (in a single bound) medium CF - 817C medium Really Big Numbers famous puzzle pupils observation: any extra can be discarded for k > 0 and will not be optimal for k = 0 physics specialists solvable with digit DP GYM - 100247F Battle Fury medium CF - 551C GukiZ hates Boxes medium greedy predicate CF - 535C Tavas and Karafs medium math, induction proofs pupils CF - 140C New Year Snowmen medium treemaps CF - 1063C Dwarves, Hats and Extrasensory Abilities medium CF - 377B Preparing for the Contest hard CF - 590B Chip 'n Dale Rescue Rangers hard CF - 343C Read Time hard pupils solvable with greedy seen interactive pupils Dynamic Programming Max 1D Range Sum CF - 75D Big Maximum Sum medium CF - 331A2 Oh Sweet Beaverette medium prefix/suffix processing specialists nice editorial solution specialists solvable without treemaps by considering only leftmost and rightmost intervals Max 2D Range Sum UVa - 10667 Largest Block easy UVa - 10502 Counting Rectangles easy binary search UVa - 10534 Wavio Sequence easy O(n log n) solution Topcoder IntegerSequence easy Topcoder AutoMarket easy UVa - 340D Bubble Sort Graph easy weak test cases Longest Increasing Subsequence (LIS) UVa - 10131 Is Bigger Smarter? CF - 4D Mysterious Present similar to Wavio Sequence treesets, inversion index easy easy SPOJ - MSTICK Wooden Sticks medium UVa - 11368 Nested dolls medium CF - 67D Optical Experiment specialists sortings LIS duality: sort all the pairs (W, H) W ascending, H descending, then find the longest non-increasing subsequence. medium LDS with binary search/segment tree (log n) specialists important UVa - 11456 Trainsorting medium LIS and LDS specialists important CF - 10D LCIS medium dp, hashmaps CF - 269C Greenhouse Effect medium important, easily solvable with normal DP SPOJ - SUPPER Supernumbers in a permutation hard Topcoder BridgeArrangement hard CF - 76F Tourist hard geometric transformations UVa - 1196 Tiling Up Blocks hard segment/fenwick tree specialists geometry, SSSP on DAG specialists SPOJ - MCARDS Card Sorting hard Knapsack UVa - 1250 Robot Challenge easy CF - 18D Seller Bob easy SPOJ - FARIDA Princess Farida easy ASC 11 - H Saving Princess medium CF - 425A Sereja and Swaps medium solvable with a greedy solution flag ↗ solvable in O(n*h*s), p can be computed from n and s, instead of checking if a valid answer exist (in such case, parameter m is need), you can minimize on m dimension compression specialists GYM - 100016JTaxi medium printing the solution SPOJ - LAZYCOWS Lazy Cows medium coordinate compression CF - 730J Bottles hard plus greedy CF - 95E Lucky Country hard variant, items grouping, connected components solvable in O(n^3 log n) using bruteDP force solution and sortings simple solution O(n^3) Solution Coin Change UVa - 10626 Buying Coke medium dimension compression, state compression important Probabilities Yandex 16 Table Tennis Tournament easy CF - 167B Wizards and Huge Prize easy Numeric Compression easy ↗ knapsack, offsets add to specialists state can be optimized from (n * l * (2n)) to (n * l * n) by sorting tours Bitmasks Yandex 16 UVa - 11974 Switch The Lights easy UVa - 10503 The dominoes solitaire easy CF - 580D Kefa and Dishes ↗ knapsack easy seenX fact: enough to use switches at most once, solvable with bfs state-space search seenX UVa - 10364 Square medium dimension compression specialists solvable with backtracking UVa - 10318 Security Panel medium grids specialists solvable with backtracking (CP hint) UVa - 10149 Yahtzee medium dimension compression, tedious UVa - 11472 Beautiful Numbers medium number systems, preprocessing CF - 8C medium Looking for Order SPOJ - HIST2 Histogram specialists specialists dp body must be optimized to pass time limit medium UVa - 11832 Account Book hard offset, printing the solution UVa - 10032 Tug of War hard knapsack variant, optimization with bitmasks need bitmasks for printing the solution efficiently Digits UVa - 11258 String Partition easy CF - 509C Sums of Digits easy CF - 58E Expression hard heavy implementation leading zeros handling as DP goes from right to left, solvable with dijkstra CF - 431D Random Task hard binary search, combinatorics specialists proving montonicity of binary search nice is critical editorial solution easy DAGs medium DAGs generate function that memoizes invalid paths so it won't try them again, solvable with greedy Grids and Paths UVa - 926 Walking Around Wisely UVa - 10874 Segments CF - 2B The least round way hard print solution easy bfs, grids specialists zero special case TSP UVa - 10944 Nuts for nuts.. UVa - 11405 Can U Win? medium bfs, preprocessing UVa - 10937 Blackbeard the Pirate medium bfs, grids composite balabizoo^1 Bitonic TSP UVa - 1347 Tour easy UVa - 1096 The Islands easy Alyona and Strings Strings CF - 682D easy edit distance UVa - 10405 Longest Common Subsequence easy LCS UVa - 164 String Computer easy edit distance, print the solution UVa - 526 String Distance and Transform Process easy edit distance, print the solution CF - 56D Changing a String easy edit distance, print the solution UVa - 10100 Longest Match easy LCS UVa - 10739 String to Palindrome easy edit distance, palindromes UVa - 11151 Longest Palindrome easy palindromes, two pointers UVa - 1207 easy edit distance UVa - 10453 Make Palindrome AGTC easy palindromes, two pointers UVa - 11552 Fewest Flops easy frequency count UVa - 11022 String Factoring easy SPOJ - AIBOHP Aibohphobia easy palindromes, two pointers UVa - 10635 Prince and Princess medium LCS, LIS CF - 137D medium palindromes, two pointers, printing the solution Palindromes 10.4 composite CF - 159D Palindrome pairs medium CF - 835D Palindromic characteristics medium palindromes (check and count) Tiling (Counting) UVa - 10918 Tri Tiling UVa - 11471 Arrange the Tiles ASC 10 - E Long Dominoes GYM - 100204BHexagon and Rhombic Dominoes easy medium hard (bitmasks) balabizoo^1 bitmasks, tiling solvable with backtracking by reducing search space by group tiles of the same type base number systems good problem to handle masks for ↗ base number systems > 2 hard work on half and combine by counting best solution DP involving graphs UVa - 976 Bridge Building UVa - 868 Numerical Maze SPOJ - CLEANRBT Cleaning Robot easy flood fill, grids easy grids, bfs important, fancy bitmasks, bfs composite medium 11.1 DP speed-up with matrix power UVa - 10229 Modular Fibonacci easy 1D recurrence, basic ASC 1 - E easy 2D recurrence, bitmasks UVa - 10518 How Many Calls? easy 1D recurrence with constant term UVa - 10870 Recurrences Nice Patterns Strike Back easy 1D recurrence, standard easy 1D recurrence, standard UVa - 12470 Tribonacci CF - 222E easy 2D recurrence UVa - 10655 Contemplation! Algebra Decoding Genome medium 1D recurrence UVa - 11486 Finding Paths in Grid medium 2D recurrence, combinations CF - 621E medium 2D recurrence, modular arithmetic Codechef - WW2 World War 2 medium 2D recurrence, different T matrices CF - 582B Once Again... medium maximization, paths in graph SPOJ - SPP Recursive Sequence (Version II) medium Wet Shark and Blocks ↗ solvable with lis and DP on DAGs DP speed-up with convex hull CF - 319C Kalila and Dimna in the Logging Industry ASC 43 - I IQ Test easy easy SPOJ - ACQUIRE Land Acquistion medium SPOJ - APIO10A Commando medium SPOJ-NKLEAVES Leaves medium CF - 311B medium Cats Transport solvable in O(n^2) ↗ NOTE: bad test data, to avoid overflow either use doubles (not recommended) or compare L3/L2 and L1/L2 instead of L3/L1 and L1/L2 (some kind of 7afraka though it's acceptable with such silly judge) DP speed-up with Divide and Conquer Optimization HackerRank Guardians of the Lunatics easy CF - 321E Ciel and Gondolas easy Codechef - CHEFAOR Chef and Bitwise OR Operation hard WF 2016 hard Branch Assignment ↗ must be solved in O(KN) for full score, observation: A function is monotonic row and column wise, so telescoping series can reduce search space (same idea of knuth's optimization but table must be filled in different order) ↗ graphs DP speed-up with Knuth Optimization UVa - 10304 Optimal Binary Search Tree SPOJ - BRKSTRNG Breaking String ASC 10 - C Order-Preserving Codes easy easy TLE java ↗ medium DP speed-up with Data Structures HackerRank Billboards medium priority queue CF - 314C Sereja and Subsequences medium fenwicktree, counting, sequences ↗ Non Classical UVa - 11703 sqrt log sin very easy UVa - 10003 Cutting Sticks easy UVa - 104 easy Arbitrage UVa - 10482 The Candyman Can easy UVa - 11407 Squares easy UVa - 10069 Distinct Subsequences easy UVa - 222 easy Budget Travel preprocessing 8.2 solvable with floyd-warshall dimension compression counting UVa - 10081 Tight Words easy counting, BigDecimal UVa - 11002 Towards Zero easy offset CF - 698A Vacation easy CF - 706C Hard problem easy CF - 82D Two out of Three easy GYM - 100201D Yet Another Digit easy CF - 855B Marvolo Gaunt's Ring easy UVa - 1244 Palindromic paths medium DAGs, two pointers, palindromes, special return type, print the solution UVa - 882 printing the solution The Mailbox Manufacturers Problem medium egg dropping UVa - 10271 Chopsticks medium greedy selection UVa - 10177 (2/3/4)-D Sqr/Rects/Cubes/Boxes? medium hardcoding, combinatorics, inclusion-exclusion principle UVa - 10419 Sum-up the Primes medium sieve, print the solution, compare function design UVa - 10690 Expression Again medium bottom-up, subset sum UVa - 11701 Cantor medium circular recurrence handling, number systems CF - 132C Logo Turtle medium UVa - 1240 ICPC Team Strategy medium bitmasks CF - 33C Wonderful Randomized Sum medium prefixes and suffixes CF - 321B Ciel and Duel medium DP idea CF - 466D Increase Sequence medium counting CF - 393D Tower of Hanoi medium SPOJ - MIXTURES Mixtures medium CF - 225C Barcode medium CF - 404D Minesweeper 1D medium CF - 383D Antimatter medium offsets, counting GYM - 100200F Think Positive medium printing the solution Topcoder EncodingTrees medium counting CF - 999F Cards and Joy medium CF - 933A A Twisty Movement medium brute force CF - 909C Python Indentation medium counting CF - 1000D Yet Another Problem On a Subsequence medium CF - 1114D Flood Fill medium CF - 1176F Destroy it! medium CF - 855E Salazar Slytherin's Locket hard CF - 13C Sequence hard UVa - 10029 Edit Step Ladders hard UVa - 11285 Exchange Rates hard UVa - 711 Dividing up hard CF - 279E Beautiful Decomposition hard ASC 36 - B Divisible Substrings very hard solvable with doubles seen seenX 10.0 important solvable with mathematical formulas (generating functions and perturbation) malformed input: has empty lines important Matrix Chain Multiplication, prefix sum offset trick for complexity O(nm + m (y-x)) instead of O(nm + my) neat implementation nice technique: has D&C + DP solution, check editorial tutorial: nice correlation with LCS mod state masks, digits trie composite, Malformed input: has uppercase letters important solvable with backtracking + search space reduction solvable with greedy ↗ grammars, modular arithmetic, D&C Other Techniques UVa - 11536 Smallest Sub-Array easy sliding window pupils constraints: K >= 1 UVa - 1121 easy sliding window pupils if no answer print 0 Subsequence solvable with backtracking and pruning solvable with greedy CF - 701C They Are Everywhere easy sliding window CF - 378B Semifinals easy two pointers CF - 239B Easy Tape Programming easy next processing CF - 190C STL easy recursion, EBNF UVa - 442 Matrix Chain Multiplication easy D&C, EBNF, bracket matching CF - 224B Array medium D&C, constructive algorithms CF - 69E Subsegments medium sliding window, treemaps, treesets CF - 57B Martian Architecture medium lazy processing CF - 89C Chip Play medium path compression, brute force, grids CF - 56E Domino Principle medium path compression, sortings CF - 375B Maximum Submatrix 2 medium next processing, brute force CF - 279C Ladder medium next processing CF - 237C Primes on Interval medium sliding window, primes CF - 1148B Born This Way medium two pointers CF - 1175C Array Splitting medium prefix sum, sortings GYM - 100008D Largest Square medium sliding window CF - 1175E medium binary lifting, lazy update GYM - 100197D Little Jumper hard ternary search, projectile trajectory CF - 888G hard D&C, constructive algorithms Xor-MST solvable with simulation easy GYM - 100201IRailroad Sort Minimal Segment Cover pupils pupils solvable with binary search + prefix sum pupils Boruvka's algorithm Data Structures Linear Data Structures 1D Array Manipulation CF - 236A Boy or Girl easy 1D Array manipulation UVa - 10050 Hartals easy CF - 988A Diverse Team easy boolean arrays CF - 1015A Points in Segments easy boolean arrays CF - 66E Petya and Post hard pupils specialists 2D Array Manipulation UVa - 10908 Largest Square easy UVa - 11975 Tele-loto easy UVa - 11581 Grid Successors easy simulation, bitmasks UVa - 201 easy brute force Squares walk on square cantor UVa - 12398 NumPuzz I easy UVa - 12187 Brothers easy UVa - 11835 Formula 1 easy brute force CF - 90B African Crossword easy implementation, strings UVa - 541 Error Correction CF - 411B Multi-core Processor CF - 706E Working routine pupils pupils medium hard reference manipulation Stack CF - 547B Mike and Feet medium effective range of a point important CF - 5C Longest Regular Bracket Sequence medium bracketing important CF - 601B Lipshitz Sequence medium effective range of a point CF - 817D Imbalanced Array medium Queue UVa - 12100 Printer Queue easy UVa - 11034 Ferry Loading IV easy UVa - 127 "Accordian" Patience UVa - 10901 Ferry Loading III easy easy stacks, references specialists simulation SPOJ - BRICKS New bricks disorder medium frequency count, counting CSA Minimize Max Diff medium modified queue CF - 788A Functions again medium modified queue Code note: don't add the mod, overflow works! ↗ Deque UVa - 12207 That is Your Queue easy UVa - 11491 Erasing and Winning medium greedy UVa - 11760 Brother Arif, Please feed us! easy bitsets CF - 60A easy bitsets Bit Manipulation Where Are My Flakes? UVa - 11933 Splitting Numbers easy CS easy Max Or Subarray GYM - 100863 Lamps (L) of the Mind hard pupils ↗ bitsets (own library), brute force Non-linear Data Structures UVa - 11849 CD treesets pupil easy treemaps, prefix sum pupils Chat Order easy treesets pupils UVa - 11286 Conformity easy treemaps UVa - 10138 CDVII easy treemaps, sortings, implementation UVa - 11136 Hoax or what easy treemaps UVa - 10282 Babelfish easy treemaps UVa - 11062 Andy's Second Dictionary easy treesets UVa - 11967 Hic-Hac-Hoe easy treesets, infinite grids, brute force CF - 105A Transmigration easy treemaps CF - 702B Powers of Two easy treemaps, brute force CF - 75B Facetook Priority Wall easy treemaps, sortings, implementation CF - 87B Vasya and Types easy tree/hashmaps UVa - 156 Ananagrams easy treemaps, anagrams CF - 205D Little Elephant and Cards easy treemaps, treesets CF - 808D Array Division easy hashsets CF - 436A Feed with Candy medium priority queues CF - 721D Maxim and Array medium priority queues, constructive algorithm CF - 681C Heap Operations medium priority queues, greedy CF - 1005E1 Median on Segments (Permutations Edition) medium treemaps, arrays, ranges, counting CF - 220C Little Elephant and Shifts medium treesets, maps, cyclic shifts CF - 3D Least Cost Bracket Sequence CF - 519D A and B and Interesting Substrings CF - 637B very easy hard priority queues, greedy, bracketing pupils pupils specialists pupils specialists specialists specialists key idea: try a solution, then optimize, important Union-Find Disjoint Sets UVa - 10583 Ubiquitous Religions easy UVa - 11474 Dying Tree easy UVa - 1197 easy The Suspects GYM - 100008A Bridges and Tunnels specialists brute force, geometry specialists specialists easy UVa - 10608 Friends medium specialists CF - 28B medium specialists pSort Timus - 1671 Anansi's Cobweb medium CF - 25D medium Roads not only in Berland SPOJ - CHAINStrange Food Chain hard CF - 553C Love Triangles reverse the problem specialists hard bipartite graphs Timus - 1003 Parity hard next processing experts CF - 659F hard grids, bfs, sortings experts Polycarp and Hay cleaner solution Fenwick Trees (Binary-Indexed Trees / BIT) UVa - 12086 Potentiometers CF - 459D Pashmak and Parmida's problem CF - 597C Subsequences easy easy medium TC - floatingMedian Floating Median medium CF - 137E medium Last Chance ↗ findIndex Timus - 1470 UFOs medium 3D Fenwick Trees, Points in Space CF - 589G Hiring medium binary search, two fts CF - 961E Tufurama medium counting UVa - 11610 Reverse Prime hard sieve, binary search GYM - 100247K Three Contests hard D&C nice replacement for pq with events&sortings composite Segment Trees UVa - 12532 Interval Product easy 8.1 solvable with two BITs (one to count zeros and other to count ones) CF - 482B Interesting Array easy CF - 339D Xenia and Bit Operations easy CF - 91B Queue easy range compression CF - 242E XOR on Segment easy lazy propagation Timus - 1846 GCD 2010 lazy propagation, prefix sum Nice Editorial Solution 8.1 solvable with binary search easy CF - 52C Circular RMQ CF - 292E Copying Data CF - 474F Ant colony medium number theory CF - 380C Sereja and Brackets medium lazy propagation, prefix sum, merging CF - 555C Case of Chocolate medium coordinate compression UVa - 1232 SKYLINE medium HackerRank Cat-cation Rentals medium HackerRank Similar Pair medium CF - 629D Babaei and Birthday Cake medium easy lazy propagation easy UVa - 11402 Ahoy, Pirates! medium CF - 558E A Simple Task medium CF - 448C Painting Fence medium 8.3 8.1 offline, lazy propagation LIS with segment trees unsolved ↗ general day ↗ 8.3 8.3 frequency count solvable with DP or greedy in O(n^2). Segment tree for O(n log n) solution HackerEarth Monk meets Dynamic Array medium LIS, modifed stacks CF - 817F MEX Queries medium range compression CF - 620E New Year Tree medium CF - 671C Ultimate Wierdness hard ↗ solvable with treesets unsolved UVa - 12669 Blogger Language hard UVa - 11990 "Dynamic" Inversion hard segment + fenwick tree HackerRank hard segment trees, number theory, stacks Boxes for Toys 8.3 nice solution ↗ experts Quad Trees UVa - 297 Quadtrees UVa - 11297 Census easy 8.1 medium solvable with 2D segment trees Sparse Table UVa - 11235 Frequent Values easy RMQ specialists UVa - 12674 Go up the ultras medium RMQ specialists gcd, preprocessing specialists CF - 475D CGCDSSQ hard solvable with segment trees: combine Node(prefix, suffix, occ, first_elem, last_elem) nice editorial solution Static RSQ (Prefix Sum) UVa - 10706 Number Sequence UVa - 12028 A Gift from the Setter CF - 706B Interesting drink GYM - 100200F Think Positive CF - 675C Money Transfers GYM - 100247C Victor's Research easy easy sortings easy easy solvable with offsets medium medium Sortings Inversion Index UVa - 299 Train Swapping very easy UVa - 612 DNA Sorting very easy solvable with bubble sort very easy solvable with bubble sort UVa - 10327 Flip Sort SPOJ - INVCNT Inversion Count easy UVa - 10810 Ultra-QuickSort easy UVa - 11495 Bubbles and Buckets UVa - 11858 Frosh Week pupils easy solvable with bubble sort pupils best one pupils nice easy HackerRank Larry's Array medium CF - 540E Infinite Inversions medium fenwick trees, treemaps/sets CF - 61E Enemy is weak medium mergesort, coordinate compression ↗ pupils Others CF - 652B z-sort easy UVa - 12049 Just Prune The List easy greedy, two pointers UVa - 450 easy input parsing, output formatting, time waster easy counting sort easy bubble sort Little Black Book UVa - 11462 Age Sort CF - 686B Little Robber Girl's Zoo pupils UVa - 11269 Setting Problems medium compare function design CF - 1043E medium counting, greedy, math Train Hard, Win Easy solvable with multisets pupils pupils experts Other Data Structure UVa - 1241 Jollybee Tournament Topcoder RedBlack medium RedBlackTree with Twists Topcoder DirectoryTree medium easy heap trees with pointers balabizoo^1 Binary Trie CF - 706D Vasiliy's Multiset CF - 817E Choosing The Commander easy XORing easy experts SPOJ - SUBXOR SubXor medium XORing UVa - 11590 Prefix Lookup medium counting CF - 282E Sausage Maximization medium XORing CF - 665E Beautiful Subarrays medium XORing HackerRank Vankey and his Interview hard XORing Solution with BitVector SQRT Decomposition CF - 617E XOR and Favorite Number medium mo Treaps SPOJ - HORRIBLE Horrible Queries easy GYM - 100488L Two Heads Are Better easy Codechef - PALINDR Lucy and Palindromes medium POJ SuperMemo medium CF T-shirts hard easily solvable with segment trees solvable with stacks and deque combinatorics ↗ Graphs Basic Algorithms CF - 540C easy flood fill UVa - 10004 Bicoloring easy Bipartite Graph Check UVa - 11686 Pick up sticks Ice Cave easy topological sort UVa - 11561 Getting Gold easy grids, dfs UVa - 10507 Waking up brain easy direct connectivity check CF - 246D Colorful Graph easy graph representation CF - 61D Eternal Victory easy dfs UVa - 11991 Easy Problem from Rujia Liu? easy graph representation UVa - 11966 Galactic Bonding easy dsu, connected components UVa - 1263 easy SCC, DAG compression, geometry UVa - 11838 Come and Go Mines easy SCC UVa - 626 Ecosystem easy connectivity, brute force CF - 691D Swaps in Permutation easy CC, sortings, permutations CF - 60B Serial Time! easy connected components, grids CF - 24A Ring road easy rings CF - 687A NP-Hard Problem easy CF - 22C System Administrator easy constructive, articulation points, star/complete graphs GYM - 100200B Burning Bridges easy standard bridges CF - 999E Reachability from the Capital easy SCC CF - 1176E Cover it! medium bipartite check CF - 103B Cthulhu medium CF - 405E Graph Cutting pupils seen pupils composite bipartite Graph Check connected components, cycle check seen medium dfs, dfs state seen UVa - 10765 Doves and bombs medium articulation points UVa - 11504 Dominos medium SCC, DAG compression UVa - 11396 Claw Decomposition medium UVa - 295 bipartite Graph Check seen medium connected components, binary search, geometry seen UVa - 10973 Triangle Counting medium graph representation, brute force seen CF - 106D Treasure Island medium grids, brute force, next processing (with counting) CF - 427C Checkposts medium SCC CF - 558C Amr and Chemistry medium bfs, implicit graph, brute force CF - 680E Bear and Square Grid medium connected components, grids, 2D sliding window CF - 723D Lakes in Berland medium connected components, grids CF - 723F st-Spanning Tree medium connected components, dsu, greedy CF - 598D Igor In the Museum medium connected components, grids GYM - 100201H Don’t Go Left medium dfs, cycles SPOJ - CAPCITY Capital City medium SCC SPOJ - BOTTOM The Bottom of a Graph medium SCC CF - 329B Biridian Forest medium bfs CF - 1063B Labyrinth medium Fatman seen seen seen seen seen put in plan seen bfs hint: enough to minimize left or right. because R - L = const UVa - 10876 Factory Robot hard connected components, binary search, geometry composite UVa - 1092 hard graph compression, grids, connectivity solvable with brute force UVa - 13008 Exposing corruption hard bipartite coloring, DP composite CF - 196B Infinite Maze hard bfs, cycles nice editorial solution CF - 788C Tracking Bio-bots The Great Mixing hard bfs, smallest cycle length, math CF - 987F AND Graph hard connected components, bitmasks CF - 369D Valera and Fools hard bfs, counting Minimum Spanning Tree (MST) UVa - 11857 Driving Range easy UVa - 1160 X-Plosives easy UVa - 544 Heavy Cargo easy maximin UVa - 10147 Highways easy minimum spanning subgraph UVa - 10397 Connect the Campus easy minimum spanning subgraph UVa - 1174 easy IP-TV 8.4 10.4 UVa - 10099 The Tourist Guide easy maximin UVa - 10462 Is There A Second Way Left? easy 2nd mst UVa - 1208 easy Oreon solvable with FW specialists solvable with FW easy max spanning tree UVa - 10369 Arctic Network easy minimum spanning forest UVa - 1235 easy pupils GYM - 100204H Oil Deal medium add to plan UVa - 11267 The Hire-a-Coder Business Model medium accept -ve weights, bipartite check UVa - 10307 Killing Aliens in Borg Maze hard SSSP, bfs, grids UVa - 1040 The Traveling Judges Problem hard brute force on all subsets, dfs, output formatting CSA Fold Polygon hard malformed input: empty line after last test case specialists UVa - 10842 Traffic Flow Anti Brute Force Lock count edges not taken by kruskal specialists solvable with binary search and DSU specialists composite ↗ Single-Source Shortest Path UVa - 11792 Krochanska is Here! easy UVa - 10422 Knights in FEN easy UVa - 11693 Speedy Escape easy binary search UVa - 12135 Switch Bulbs easy bfs, bitmasks, state-space search UVa - 928 easy bfs, grids, state-space search UVa - 12160 Unlock the Lock easy bfs UVa - 710 Eternal Truths The Game bfs needs good complexity analysis composite specialists easy dijkstra, grids UVa - 10047 The Monocycle easy bfs, grids, state-space search UVa - 11487 Gathering Food medium bfs, counting paths UVa - 859 medium bfs UVa - 11635 Hotel booking medium dijkstra, state-space search UVa - 12070 Invite Your Friends medium dijkstra, grids, state-space search, brute force UVa - 10557 XYZZY medium bellman-ford, maximization, connectivity, positive cycles specialists important UVa - 11721 Instant View of Big Bang medium bellman-form, negative cycles, printing the solution specialists important, solvable with SCC UVa - 1233 USHER medium single-sink, dijkstra, bottle replacement (combinatorics) CF - 59E Shortest Path medium bfs, state-space search, printing the solution CF - 96D Volleyball Chinese Checkers medium graph conversion GYM - 100200H Driving Straight medium bfs, printing the solution CF - 229B Planets medium dijkstra, binary search, sets CF - 342C Paths and Trees medium CF - 144D Missile Silos medium CF - 716D Complete The Graph specialists composite specialists specialists put in plan hard check this comment UVa - 10166 Travel hard dijkstra solvable with DP UVa - 1202 hard dijsktra, grids speical case: outside grid Finding Nemo CF - 100570B ShortestPath Query hard All-Pairs Shortest Path (Floyd-Warshall's Algorithm) UVa - 12319 Edgetown's Traffic Jams easy seen UVa - 567 Risk easy standard UVa - 821 Page Hopping solvable with BFS but graph is small easy standard UVa - 11047 The Scrooge Co Problem easy standard specialists UVa - 1056 seenX Degrees of Separation easy standard UVa - 10171 Meeting Prof. Miguel... easy standard UVa - 925 No more prerequisites, please! easy transitive closure, transitive reduction of a DAG UVa - 439 Knight Moves easy UVa 423 MPI Maelstrom easy UVa - 521 Gossiping medium graph connectivity, lcm UVa - 125 Numbering Paths medium counting paths UVa - 334 Identifying Concurrent Events medium connectivity, transitive closure, topological sort + fenwick trees (for large graphs) UVa - 1243 Polynomial-time Reductions hard non-zero diagonal, printPath edit specialists specialists transitive closure, SCC, transitive reduction of a DAG specialists specialists misconception constraints: small graph specialists Network Flow UVa - 563 Crimewave CF - 498C Array Operations easy output sensitive complexity medium number theory GYM - 100200A Unique Attack medium min cut, Dinic with scaling Topcoder Graduation medium UVa - 10983 Buy one, get the rest free hard important, customization of max flow solution, solvable with bipartite matching binary search, max flow balabizoo^3 Minimum Cost (Max) Flow UVa - 10806 Dijkstra, Dijkstra. medium minimum cost flow UVa - 10746 Crime Wave - The Sequel medium MCMF on bipartite graph UVa - 10594 Data Flow medium minimum cost flow UVa - 11301 Great Wall of China medium MCMF with SPFA, grids, vertex capacity UVa - 10888 Warehouse medium SSSP (bfs), MCMF on bipartite graph CF - 863F Almost Permutation medium Guess Your Way Out! easy Trees CF - 507C binary tree, heap representation UVa - 11350 Stern-Brocot Tree easy CF - 682C Alyona and the Tree easy max suffix sum UVa - 615 Is It A tree? easy dfs UVa - 11108 Tautology easy expression evaluation, btimasks, brute force UVa - 699 The Falling Leaves easy pre-order UVa - 679 Dropping Balls easy heap representation UVa - 12186 Another Crisis easy dfs, sortings UVa - 599 The Forrest for the Trees easy tree properties CF - 698B Fix a Tree easy dfs, constructive algorithm CF - 34D Road Map easy stacks CF - 369C Valera and Elections easy tree traversal GYM - 100247E Of Groups and Rights Topcoder IncompleteBST CF - 763A Timofey and a tree checking for a tree using indegree and #edges is not enough in case of description using defined root and directed edges is not enough (cases: empty tree, loops, disconneted + cycle) balabizoo^2 balabizoo^2 seen easy easy implementation easy UVa - 11131 Close Relatives medium CF - 675D medium Tree Construction general day tree traversal general day general day UVa - 11234 Expressions medium post-order or level order, binary tree, stacks, queues CF - 82C General Mobilization medium implementation, priorityqueues CF - 89B Widget Library medium implementation, dp, treemaps, expression parsing CF - 77C Beavermuncher-0xFF medium dfs, greedy CF - 337D Book of Evil medium tree diameter, dfs CF 486D Valid Sets medium dfs, combinatorics CF - 707D Persistent Bookcase medium dfs, persistence CF - 455C Civilization medium diameter, dsu CF - 570D Tree Requests hard euler walk, prefix xor, bitmasks, binary search UVa - 10805 Cockroach Escape Networks hard minimum diameter spanning tree can be solved with segment trees solvable with up & down dp Nice Solution 11.3 important DP on Trees Topcoder PendingTasks easy UVa - 11307 Alternative Arborescence medium DP, min chromatic sum CF - 440D Berland Federalization medium firstChild & nextSibling CF - 110E Lucky Tree medium up & down dp CF - 219D Choosing Capital for Treeland medium up & down dp CF - 618D Hamiltonian Spanning Tree medium firstChild & nextSibling CF - 855C Helga Hufflepuff's Cup medium firstChild & nextSibling CF - 500D New Year Santa Network medium up & down, expectations SPOJ - VOCV Con-Junctions medium DP CF - 461B medium counting Appleman and Tree only 6 colors are needed for largest n solvable with 1 dfs Euler Walk CF - 343D Water Tree medium segment trees CF - 397E On Changing Tree medium segment trees CF - 838C Propagating tree medium fenwick trees CF - 570D Tree Requests seen hard solvable with DSU on trees Lowest Common Ancestor (LCA) LA - 2045 Closest Common Ancestors UVa - 10938 Flea circus easy standard easy experts UVa - 12238 Ants Colony easy experts GYM - 100015F City Driving medium experts UVa - 12533 Joining Couples medium experts CF - 191C Fools and Roads medium experts CF - 855D Rowena Ravenclaw's Diadem medium UVa - 1728 Toll Management IV hard experts DSU on Trees CF - 600E Lomsat gelral easy CF - 246E Blood Cousins Return medium multisets CF - 208E Blood Cousins medium ancestors processing CF - 161D Distance in Tree medium solvable with euler walk and LCA solvable with DP in O(nk) Centroid Decomposition CF - 321C Ciel the Commander IOI 2011 Race CF - 342E Xenia and Tree easy standard easy aux array medium ↗ best complexity: O(N log N) SPOJ - QTREE5 Query on a tree V medium multisets Hello 2015 - Div1 TreeF Query medium binary search CF - 716E Digit Tree medium modular inverse, up & down dp HackerRank BST Maintenance hard BST construction ↗ HackerRank Unique Colors hard auxilary array ↗ easy binary search MCBM Bipartite Graph UVa - 11262 Weird Fence best complexity: O(N log^2 N) ↗ UVa - 753 easy MCBM UVa - 12159 Gun Fight easy MCBM, geometry UVa - 670 A Plug for UNIX The dog task easy MCBM, geometry Topcoder RookAttack easy Topcoder PlayingCubes easy Topcoder Parking MCBM easy bfs, binary search SPOJ - QUEST4 Dungeon of Death easy mvc SPOJ - TAXI Taxi easy UVa - 10804 Gopher Strategy medium UVa - 663 medium Sorting Slides UVa - 11419 SAM I AM Topcoder DataFilter medium binary search, MCBM solvable with pfs seenX composite check whether removing an edge will affect MCBM, solvable with greedy algorithm MVC, printing the solution important hard many cases, implementation details Eulerian Graph UVa - 291 The House Of Santa Claus UVa - 117 The Postal Worker Rings Once easy euler tour, backtracking easy euler tour, FW UVa - 10296 Jogging Trails medium chinese postman problem CF - 788B Weird journey medium counting CF - 62D Wormhouse hard euler tour/path, bridges CF - 367C Sereja and the Arrangement of Numbers hard euler tour, modelling problem Always on the run backtracing solution DAGs UVa - 590 easy shortest path, DP UVa - 10285 Longest Run on a Snowboard easy longest path, DP UVa - 103 easy longest path, LIS UVa - 10926 How Many Dependencies? easy counting reachable nodes, DAG balabizoo^2 UVa - 10000 Longest Paths easy longest path, DP, pair optimization balabizoo^1 UVa - 12376 As Long as I Learn, I Live easy graph traversal UVa - 10350 Liftless EME easy shortest path, DP UVa - 11545 Avoiding Jungle in the Dark medium shortest path, DP UVa - 11324 The Largest Clique medium SCC, DAG compression, DP CF - 721C medium DP, printing the solution SPOJ - TRSTAGE Traveling by Stagecoach medium DP, bitmasks UVa - 10917 Walk Through the Forest hard Stacking Boxes Journey GYM - 100863 tourist (G) very hard balabizoo^2 weak test cases seenX seenX composite dijkstra, convert general graph to DAG, count paths printing paths, DAG compression, topological sort Minimum Path Cover (MPC) UVa - 1201 Taxi Cab Scheme UVa - 1184 Air Raid easy easy Functional Graphs CF - 702E Analysis of Pathes in Functional Graph medium CF - 711D Directed Roads medium combinatorics CF - 698B Fix a Tree medium constructive algorithm Bridge Trees Arabella 2015 -Capital H City Amman 2015 -Bridges H easy tree diameter ↗ easy tree diameter ↗ CF - 555E Case of Computer Network medium LCA HackerRank Sherlock and Queries on the Graph medium LCA ↗ DSU on graphs ECPC 2015 - CConnecting Graph HackerRank Travel in HackerLand medium ↗ hard ↗ Mathematics Ad-hoc Brute Force CF - 915A Garden easy divisibility UVa - 264 Count on Cantor easy grid UVa - 697 Jack and Jill easy simulation UVa - 616 Coconuts, Revisited medium UVa - 10257 Dick and Jane medium UVa - 10427 Naughty Sleepy Boys medium rational numbers enumeration filtered divisibility, coprimes complex output formatting observation: remaining coconuts on last day must be at least N * (N-1) mathematical insight brute force Formulas CF - 415B Mashmokh and Tokens easy floor and ceiling UVa - 10696 f91 easy UVa - 10970 Big Chocolate easy UVa - 10014 Simple calculations easy CF - 638A Home Numbers easy CF - 70A Cookies easy CF - 80B Depression easy CF - 90A Cableway easy UVa - 913 Joana and the Odd Numbers CF - 787A The Monster CF - 233B Non-square Equation medium quadratic equation, brute force CF - 185A Plant medium fast exponentiation CF - 702D Road to Post Office medium linear recurrence easy easy UVa - 10519 !! Really Strange !! medium geometry, arithmetic progression CF - 337C medium floor and ceiling, fast exponentiation Quiz solvable with DP with matrix power Logarithms and Powers UVa - 113 Power of Cryptography UVa - 11636 Hello World! UVa - 107 The Cat in the Hat easy easy medium W must be pow(N, k) and H must be pow(N+1, k) for some k, 1 special case Polynomials UVa - 392 Polynomial Showdown UVa - 12318 Digital Roulette easy polynomials, output formatting easy Ruffini–Horner's method, brute force, treesets bitwise or, couting filtered useless Base Number Systems CF - 1017B The Bits easy UVa - 575 Skew Binary easy CF - 92B Binary Number easy UVa - 10931 Parity easy UVa - 11185 Ternary easy CF - 219B Special Offer! Super Price 999 Bourles! easy UVa - 389 Basically Speaking CF - 39H Multiplication Table GYM - 100008B Alien Communicating Machines GYM - 100201C Yellow Code toBinaryString(), bitCount() easy solvable with built-in functions only easy easy medium bit manipulation Find the pattern CF - 55A Flea travel UVa - 10161 Ant on a Chessboard easy mathematical insights solvable with simulation hard solvable with simulation Others UVa - 496 Simply Subsets easy set operations, treesets UVa - 138 Street Numbers easy hardcoding CF - 42A Guilty — to the kitchen! easy inequalities, greedy CF - 697B Barnicle easy scientific notation UVa - 350 Pseudo-Random Numbers easy cycle finding UVa - 10591 Happy Number easy cycle finding UVa - 10013 Super long sums easy long arithmetic CF - 111A Petya and Inequiations easy greedy CF - 1175B Catch Overflow! easy infinity CF - 1176A Divide it! easy CF - 863C 1-2-3 medium CF - 65A Harry Potter and Three Spells medium CF - 81C Average Score medium mathematical insights, sortings CF - 712C Memory and De-Evolution medium greedy see proof in tutorial comments UVa - 202 Repeating Decimals medium repeating decimals, cycle finding, long division important CF - 939E Maximize! medium mean, two pointers medium dp cycle finding add to specialists Combinatorics pigeonhole Principle CF - 577B Modulo Sum Fibonacci Numbers UVa - 10579 Fibonacci Numbers very easy UVa - 11000 Bee easy UVa - 10862 Connect the Cable Wires easy dp 9.1 UVa - 10689 Yet another Number Sequence easy pisano period 9.1 9.2 UVa - 11161 Help My Brother (II) easy 9.2 UVa - 11089 Fi-binary Number medium Fibonacci Number System UVa - 11780 Miles 2 Km medium fibonacci growth, DP UVa - 1258 Nowhere Money medium two-step interpretation, zerkendorf's theorem CF - 551D GukiZ and Binary Operations medium PE because of blanks at the end of each line solvable with DP with matrix power Binomial Coefficient CF - 919B Perfect Number easy CF - 817B Makes And The Product easy CF - 294C Shaass and Lights easy use stars and bars to prove max answer. check bonus questions in tutorial UVa - 10105 Polynomial Coefficients easy UVa - 326 Extrapolation Using a Difference Table easy CF - 397C On Number of Decompositions into Multipliers medium stars and bars, prime factorization ASC 28 - D Dinner Problem medium take at least 1 CF - 156C Cipher medium dp, modelling (numbers moving between buckets) CF - 128C Games with Rectangle medium CSA All Numbers medium A2oj - 292 Functions hard dp (take at least 1) HackerRank Div and Span hard catalan, dp, stars and bars CF - 57C Array hard stars and bars Catalan Numbers combinatorial proof of binomial coefficient pascal's triangle ↗ stars and bars with restriction solvable with dp with prefix sum processing combinatorial solution ↗ preprocessing, composite ↗ UVa - 10303 How Many Trees? UVa - 10223 How many nodes ? UVa - 10312 Expression Bracketing easy 9.1 easy medium dp, super cataln numbers 9.2 important Inclusion-Exclusion Principle UVa - 10325 The Lottery easy UVa - 11806 Cheerleaders easy SPOJ - NGM2 Another Game With Numbers easy CF - 701B Cells Not Under Attack easy Topcoder Divisibility easy Topcoder SetOfPatterns easy ↗ divisible by at least one of a set Codechef - COUNTREL Count Relations SPOJ - MSKYCODE Sky Code medium square-free numbers Topcoder Carless Secretary medium free-fixed-points permutations, derangements CF - 560E Gerald and Giant Chess medium SPOJ - SQFREE Square-free integers ↗ best solution medium Derangments UVa - 10497 Sweet Child Makes Trouble easy UVa - 12024 Hats easy Topcoder easy Deranged BigInteger 11.3 Others UVa - 12463 Little Nephew easy UVa - 10079 Pizza Cutting easy formula 9.1 UVa - 11069 A Graph Problem easy dp 9.1 9.1 UVa - 11597 Spanning Subtree easy formula 8.4 UVa - 10219 Find the ways ! easy CF - 83A Magical Array easy combinations CF - 621B Wet Shark and Bishops easy chessboard 9.2 UVa - 10338 Mischievous Children easy UVa - 10790 How Many Points of Intersection? easy arithmetic progression UVa - 11554 Hapless Hedonism easy triangle counting, pattern finding, prefix sum easy counting principle easy DP UVa - 11115 Uncle Jack UVa - 10328 Coin Toss CF - 205C Little Elephant and Interval easy nice solution UVa - 11401 Triangle Counting medium brute force, formula CF - 459C Pashmak and Buses medium counting principle, constructive algorithm CF - 496D Tennis Game medium harmonic series, binary search/preprocessing CF - 258B Little Elephant and Elections medium backtracking medium DP GYM - 100015B Ball Painting 9.2 9.2 Number Theory Prime Numbers CF - 665D Simple Subset easy UVa - 543 sieve specialists easy sieve specialists UVa - 10948 The primary problem Goldbach's Conjecture easy sieve specialists UVa - 914 specialists easy sieve, binary search UVa - 10533 Digit Primes Jumping Champion easy modified sieve, static RSQ UVa - 10200 Prime Time easy sieve, static RSQ UVa - 10490 Mr. Azad and his Son!!!!! easy perfect number, sieve UVa - 10852 Less Prime easy sieve, modulo UVa - 10650 Determinate Prime easy sieve Topcoder EngineersPrimes specialists solvable with hardcoding seen easy sieve UVa - 10871 Primed Subsequence easy sieve, brute force UVa - 967 Circular easy sieve, static RSQ specialists CF - 385C Bear and Prime Numbers easy sieve, static RSQ specialists UVa - 10858 Unique Factorization medium backtracking UVa - 11752 The Super Powers medium UVa - 10742 The New Rule in Euphomia medium sieve, static RSQ, combinatorics Topcoder PreprimeNumbers medium sieve, brute force, sortings Topcoder PowerCollector medium Topcoder PrimePalindromic medium sieve, brute force Topcoder PrimePolynom medium primality test, brute force Topcoder PrimeAnagrams medium sieve, brute force seen 10.0 Modular Arithmetic CF - 913A Modular Exponentiation very easy CF - 447A DZY Loves Hash very easy CF - 68A Irrational problem very easy UVa - 10127 Ones very easy UVa - 1230 MODEX very easy CF - 248B Chilly Willy pupils conceptual problem seen easy optimizations UVa - 10489 Boxes of Chocolates easy filtered unclear problem statement UVa - 128 Software CRC easy filtered unclear problem statement CF - 284A Cows and Primitive Roots easy seen CF - 332A Down the Hatch! easy CF - 132A Turing Tape easy UVa - 374 Big Mod easy UVa - 10176 Ocean Deep! - Make it shallow!! easy CF - 677B Vanya and Food Processor easy CF - 1175A From Hero to Zero CF - 476C Dreamoon and Sums fast exponentiation seen discussed easy medium quotient remainder theorem specialists UVa - 10212 The Last Non-zero Digit medium UVa - 10174 Couple-Bachelor-Spinster Numbers. medium UVa - 11029 Leading and Trailing medium logarithmic trick, big mod trick specialists UVa - 10006 Carmichael Numbers medium fast exponentiation, precomputation specialists CF - 300C Beautiful Numbers medium modular inverse, combinatorics specialists UVa - 133 The Dole Queue medium circular arrays specialists CF- 321A Ciel and Robot medium GYM - 100015A Another Rock-Paper-Scissors Problem medium Topcoder DivisibilityCriteria medium CF - 303A Lucky Permutation Triple medium GYM - 100204IBishops on a Toral Board medium UVa - 11155 Be Efficient hard CF - 492E Vanya and Field hard CF - 484B Maximum Value hard GCD and LCM UVa - 11388 GCD LCM very easy specialists specialists odd check for negative numbers, square difference modular equations offsets easily solvable with prefix mod array experts harmonic series, next processing UVa - 11417 GCD very easy CF - 664A Complicated GCD easy specialists seen UVa - 408 Uniform Generator easy specialists seen UVa - 412 Pi easy CF - 75C Modified GCD easy binary search, divisors generation UVa - 332 Rational Numbers from Repeating Fractions easy fraction simplification UVa - 10892 LCM Cardinality easy divisors generation seen UVa - 12068 Harmonic Mean easy fraction simplification seen easy brute force UVA - 10717 Mint CF - 678C Joty and Chocolate easy inclusion-exclusion CF - 741A Arpa's loud Owf and Mehrdad's evil plan medium permutation cycles CF - 87A Trains medium UVa - 11774 Doom's Day medium Find patttern UVa - 106 Fermat vs. Pythagoras medium pythagorean triples UVa - 10637 Coprimes medium backtracking, pruning, gcd table CF - 66D Petya and His Friends medium constructive algorithm CF - 303B Rectangle Puzzle II medium CF - 1174C Ehab and a Special Coloring Problem medium CF - 359C Prime Number hard CF - 74C Chessboard Billiard hard CF - 348B Apple Tree hard specialists special case: j = 0 specialists logic seen seen tricky cases: out of bounds harmonic solvable with dsu trees solution overflow handling Factorial UVa - 623 500! UVa - 10220 I Love Big Numbers ! UVa - 324 Factorial Frequencies UVa - 568 Just the Facts UVa - 10323 Factorial! You Must be Kidding!!! very easy BigInteger very easy BigInteger easy BigInteger easy extract last non-zero digit easy seen specialists seen filtered Prime Factorization UVa - 583 Prime Factors easy UVa - 516 Prime Land easy specialists UVa - 10392 Factoring Large Numbers easy filtered UVa - 11466 Largest Prime Divisor easy UVa - 160 Factors and Factorials easy UVa - 993 Product of digits easy UVa - 10780 Again Prime? No Time. easy UVa - 10791 Minimum Sum LCM easy UVa - 10484 Divisibility of Factors easy UVa - 10527 Persistent Numbers easy UVa - 11347 Multifactorials UVa - 11889 Benefit easy base prime number system seen weak test cases seen divisors from 9 to 2 numDivs easy UVa - 10061 How many zero's and how many digits ? medium specialists nice seen UVa - 10139 Factovisors medium specialists nice seen UVa - 10622 Perfect P-th Powers medium specialists trick: magnitude implies -ve numbers, -2^31 UVa - 10680 LCM medium specialists CF - 490D medium Chocolate #digits base b, #trailing zeros base b, factorials brute force UVa - 11395 Sigma Function hard square numbers CF - 449C hard sieve, multiples, constructive Jzzhu and Apples seen important seen composite Functions Involving Prime Factors UVa - 294 easy numDiv UVa - 11876 N + NOD (N) easy numDivs, binary search UVa - 884 Divisors easy numPF UVa - 10820 Send a Table easy phi UVa - 11728 Alternate Task easy sumDiv UVa - 11064 Number Theory easy numDiv, phi UVa - 11086 Composite Prime easy numPF UVa - 11226 Reaching the fix-point. easy sumPF, DP UVa - 1246 easy numDiv UVa - 11353 A Different Kind of Sorting easy numPF UVa - 12005 Find Solutions hard formula reduction, numDiv UVa - 10958 How Many Solutions? hard formula reduction, numDiv UVa - 10856 Recover Factorial easy numPF UVa - 10699 Count the factors easy numDiffPf UVa - 12043 Divisors easy sumDiv, numDiv, brute force UVa - 10990 Another New Function easy phi, DP, static RSQ UVa - 10738 Riemann vs Mertens easy squareFree, numPF, static RSQ specialists UVa - 11415 Count the Factorials easy numPF, static RSQ, binary search specialists UVa - 11408 Count DePrimes easy static RSQ, sumDiffPF UVa - 11960 Divisor Game easy numDiv, DP UVa - 11730 Number Transformation easy bfs, state-space search, DP, PF generation CF - 1176D easy largest divisor Factorial Factors Find Terrorists specialists seen seen specialists trick: bounds are given without order seen important seen filtered seen important Modified Sieve Recover it! solvable with DP and BS (CP chapter 8) specialists seen seen seen specialists seen composite seen Extended Euclidean Algorithm UVa - 10104 Euclid Problem UVa - 10673 Play with Floor and Ceil easy easy specialists UVa - 10090 Marbles medium diophantine equation specialists UVa - 10633 Rare Easy Problem medium diophantine equaiton specialists seen important, solvable with mathematical reduction and brute force seen Others CF - 935A Fafa and his Company very easy count divisors CF - 1047A Little C Loves 3 I very easy divisibility UVa - 11461 Square Numbers easy perfect squres UVa - 10110 Light, more light easy perfect squares UVa - 10606 Opening Doors easy perfect squares, binary search, BigInteger UVa - 10929 You can say 11 easy divisibility UVa - 11344 The Huge One easy divisibility, BigInteger UVa - 11042 Complex, difficult and complicated easy complex numbers UVa - 756 easy Chinese remainder theorem UVa - 10880 Colin and Ryan Biorhythms easy divisors generation, stacks, queues CF - 43C Lucky Tickets easy divisibility CF - 597A Divisibility easy divisibility Topcoder RugSizes easy divisibility, brute force CF - 71C Round Table Knights medium divisors generation/prime factorization, brute force GYM - 100247L For the Honest Election medium divisors generation Topcoder Refactoring medium divisors generation, dp Topcoder DivisorInc medium divisibility, dp seen seen Topcoder SquareFree CF - 448E Divisors medium moebius function hard divisors generation, D&C easy observation optimization with sieve to handle prime observation: numbersall divisors of divisors of a number seen are divisors of that number, generate Divisors DAG in O(cubic_root(x)^2 + sqrt(x)) Permutations CF - 359B Permutation CF - 180F Mathematical Analysis Rocks! UVa - 10098 Generating Fast UVa - 11371 Number Theory for Newbies UVa - 941 Permutations easy easy next_permutation easy medium kth permutation UVa - 11525 Permutation medium kth permutation, segment trees UVa - 11282 Mixing Invitations medium fixed points CF - 67B Restoration of the Permutation medium constructive algorithm CF - 48D Permutations medium constructive algorithm composite Probability Theory CF - 77B easy continuous probability UVa - 10491 Cows and Cars UVa - 542 Falling Anvils easy formula France '98 easy D&C UVa - 10056 What is the Probability ? easy formula UVa - 11628 Another lottery easy UVa - 12114 Bachelor Arithmetic easy Topcoder BenfordsLaw Topcoder ProbabilityTree easy expected value easy bfs, conditional probability UVa - 11181 Probability|Given medium conditional probability UVa - 12461 Airplane medium :"D CF - 107B Basketball Team medium combinatorics CF - 109B Lucky Probability medium brute force, lucky numbers generation Topcoder RangeGame medium Topcoder ChipRace medium dp Topcoder GeneticCrossover medium dfs Topcoder BagOfDevouring medium dp, bitmasks Topcoder RandomFA medium dp Topcoder AntiMatter medium gcd CF - 1042E Vasya and Magic Matrix hard expectation, dp, algebra CF - 235B Let's Play Osu! hard expectation UVa - 11500 Vampires hard gambler's ruin problem Topcoder TestScores hard mean and standard deviation Topcoder PackageShipping hard dp Topcoder Hangman42 hard dp easy DP easy addition rule, independent events easy DP corner cases nice solution restate the problem, important combinatorics trick Probability with DP UVa - 10759 Dice Throwing Topcoder PrimeSoccer Topcoder TopFive UVa - 11021 Tribles medium DP, independent events hard bitmasks, preprocessing UVa - 10891 Game of Sum easy dp, two pointers UVa - 10404 Bachet's Game easy dp UVa - 10578 The Game of 31 easy dp UVa - 11489 Integer Game easy strategy finding UVa - 10536 Game of Euler medium dp, bitmasks GYM - 100015F Fighting for Triangles medium dp UVa - 847 medium strategy finding UVa - 10111 Find the Winning Move medium dp, implementation UVa - 10368 Euclid's Game medium pattern finding UVa - 12293 Box Game medium pattern finding UVa - 12469 Stones medium dp or pattern finding CF - 69D Dot medium dp CF - 63E Sweets Game medium dp, bitmasks, preprocessing CF - 538E Demiurges Play Again medium trees, constructive Topcoder CakeParty CF - 16E Fish solvable with backtracking ↗ Solve it on SPOJ with Java Game Theory Decision Tree (Minimax Strategy) A Multiplication Game hard strategy finding Nim Game UVa - 10165 Stone Game UVa - 11311 Exclusively Edible CF - 15C Industrial Nim Topcoder StoneGameStrategist very easy easy medium hard xor on interval important ladder nim Sprague-Grundy Theorem UVa - 11534 Say Goodbye to Tic-Tac-Toe Codechef - ASTRGAME A String Game SPOJ - MATGAME Matrix Game Timus - 1465 Pawn Game easy easy medium easy CF - 317D Game with Powers medium CF - 335C More Reclamation medium CF - 87C Interesting Game hard dp Topcoder LongLongNim hard hardcoding with dp cycle finding Topcoder Roxor hard CF - 959A Mahmoud and Ehab and the even-odd game easy strategy finding CF - 74B Train easy greedy, simulation CF - 79A Bus Game easy simulation CF - 914B Conan and Agasa play a Card Game medium strategy finding CF - 78C Beaver Game medium strategy finding CF - 49D Game medium brute force CF - 55C Pie or die medium strategy finding CF - 705B Spider Man medium CF - 197A Plate Game medium CF - 388C Fox and Card Game nice solution Others hard game = # cuts in a chocolate bar strategy finding greedy BigInteger UVa - 424 Integer Inquiry very easy BigInteger addition UVa - 10193 All You Need Is Love easy gcd UVa - 10235 Simply Emirp easy Probabilistic primality test UVa - 10494 If We Were a Child Again easy long divison and modulo Others try implementing it without BigInteger UVa - 10164 Number Game UVa - 547 DDF hard medium parity sequences, numDiv, DP tricky input Canonical Form CF - 560D Equivalent Strings medium general day Strings Ciphering UVa - 10878 Decode the tape easy observation Frequency Count CF - 43B Letter easy UVa - 11588 Image Coding easy 2D Arrays CF - 50B easy counting principle Choosing Symbol Pairs UVa - 10252 Common Permutation easy CF - 1176C Lose it! medium CF - 551B ZgukistringZ medium CF - 335A Banana medium brute force, greedy CF - 254C Anagram medium subsequences greedy pupils pupils specialists Subsequences UVa - 10340 All in All CF - 91A Newspaper Headline easy medium subsequence check next occurence processing Regular Expression (Regex) UVa - 409 Excuses, Excuses! easy String Matching CF - 79C Beaver easy two pointers, greedy CF - 23A You're Given a String... easy brute force CF - 39J Spelling Check easy prefix/suffix matching easy string compression UVa - 10298 Power Strings easy string compression UVa - 11576 Scrolling Sign easy UVa - 11475 Extend to Palindrome easy suffix palindromes UVa - 11888 Abnormal 89's easy prefix/suffix palindromes UVa - 12467 Secret Word easy palindromes UVa - 886 Prefix Function (KMP) UVa - 455 Periodic Strings Named Extension Dialing easy treesets SPOJ - NHAY A Needle in the Haystack easy standard, on the fly CF - 535D Tavas and Malekas easy CF - 126B Password medium CF - 346B Lucky Common Subsequence medium HackerRank Cutting the String hard counting, string compression CF - 25E Test hard permutations, greedy Topcoder InfiniteSoup hard number theory CF - 471D MUH and Cube Walls hard solvable with Z-Algorithm DP, prefix automaton ↗ clever optimizations solvable with rabin-karp (+ modified queues) Aho Corasick UVa - 10679 I Love Strings!! easy codechef - LYRC Music & Lyrics easy codechef - QMARKS Lucy and Question Marks easy dp codechef - FAVNUM Favourite Numbers medium dp CF - 163E medium euler walk, fenwick tree e-Government easily solvable with suffix automaton ↗ duplicate dictionary words needs (time & memory) optimization, ↗ ↗ sensitive to time & memory Grids UVa - 10010 Where's Waldorf? easy backtracking, pruning UVa - 422 Word-Search Wonder easy backtracking, pruning UVa - 604 The Boggle Game easy backtracking, generation, treesets UVa - 11283 Playing Boggle easy backtracking, pruning UVa - 736 easy backtracking, pruning easy distinct substrings Lost in Space uDebug hint Suffix Structures Suffix Trie CF - 271D Good Substrings UVa - 760 DNA Sequencing easy LCS experts CF - 113B Petr# medium KMP experts CF - 456D A Lot of Games medium game theory, min-max strategy SPOJ - MORSE solvable with hashing hard DP TYPO: A word can exist more than once in dictionary, deal with them as different words UVa - 11512 GATTACA easy longest repeated substring solvable with suffix trie UVa - 11107 Life Forms hard LCS variant, modified queues, sliding window solvable with suffix automaton SPOJ - SUBLEX Lexicographical Substring Search easy kth substring optimize for time > memory UVa - 719 Glass Beads easy smallest cyclic shift UVa - 1223 Editor easy longest repeated substring CF - 427D Match & Catch UVa - 1254 Top 10 hard substring occurence UVa - 257 Palinwords easy brute force CF - 70B Text Messaging easy expression parsing, greedy CF - 61B Hard Work easy expression parsing, brute force CF - 59C Title easy palindromes, greedy CF - 81B Sequence Formatting easy expression parsing CF - 34C Page Numbers easy expression parsing, output formating UVa - 644 Immediate Decodability easy CF - 278B New Problem easy brute force, treesets CF - 777D Cloud of Hashtags easy greedy CF - 62B Tyndex.Brome medium next/last occurence preprocessing CF - 56C Corporation Mail medium expression parsing, treemaps medium canonical form Suffix Array Suffix Automaton medium occurences solvable with DP in O(n^2) - check editorial Others GYM - 100247B Similar Strings filtered solvable with built-in function StartsWith() nice solution String Hashing SPOJ - ADACLEAN Ada and Spring Cleaning easy CF - 245H Queries for Number of Palindromes medium CF - 494B Obsessive String medium rabin-karp solvable with DP rabin-karp, dp solvable with KMP root a aa ab Geometry Points and Lines UVa - 152 Tree's Crowd CF - 706A Beru-taxi very easy easy brute force UVa - 10263 Railway easy closest point to line segment UVa - 10357 Playball !!! easy UVa - 587 There's treasure everywhere! easy translation, path tracing, simulation UVa - 378 Intersecting Lines easy line intersection pupils UVa - 10585 Center of Symmetry easy CF - 498A Crazy Town easy UVa - 184 Laser Lines easy collinear test, brute force CF - 667A Pouring Rain easy physics UVa - 10167 Birthday Cake easy brute force UVa - 273 Jack Straws easy line segment intersection, dsu, connected components UVa - 356 Square Pegs And Round Holes easy brute force CF - 257C View Angle easy CF - 1047B Cover Points easy UVa - 191 Intersection medium UVa - 837 Light and Transparencies medium 7.4 UVa - 920 Sunny Mountains medium 7.1 7.4 specialists solvable with FW line equation rectangle-line segment intersection 7.3 two opposite corners are given not necessarily top left and bottom right UVa - 10250 The Other Two Trees medium translation 7.2 parallelogram not rectangle UVa - 10466 How Far? medium UVa - 10902 Pick-up Sticks medium segment-segment intersection 7.1 clarification: maximum number of sticks at any moment = 1000 CF - 671A Recycling Bottles medium sortings CF - 593B Anton and Lines medium sortings CF - 65C Harry Potter and the Golden Snitch medium binary search, physics CF - 552D Vanya and Triangles medium brute force, counting, treemaps CF - 404B Marathon medium modular arithmetic GYM - 100201B The Minimal Angle medium rotations, formula CF - 1032D medium Barcelonian Distance UVa - 11894 Genius MJ hard UVa - 11519 Logo 2 hard UVa - 11574 Colliding Traffic hard brute force, formula derivation, physics CF - 590B hard binary search, physics Chip 'n Dale Rescue Rangers GYM - 100015E Empty Triangles transformation EPS handling: read editorial specialists 7.4 7.3 solvable with binary search hard my solution: O(n^2 log n). Package solution with hashmaps and sets O(n^3) Triangles (plus Circles) UVa - 438 The Circumference of the Circle UVa - 11152 Colourful Flowers very easy very easy 7.2 UVa - 143 Orchard Trees easy inside triangle CF - 766B Mahmoud and a Triangle easy sorting UVa - 10195 The Knights Of The Round Table easy CF - 1C easy Ancient Berland Circus UVa - 10286 Trouble with a Pentagon easy UVa - 10991 Region easy UVa - 10210 Romeo and Juliet ! medium UVa - 10387 Billiard medium UVa - 10577 Bounding Box medium UVa - 10792 The Laurel-Hardy Story medium UVa - 11909 Soya Milk medium UVa - 10734 Triangle Partitioning medium CF - 407A medium Triangle UVa - 11164 Kingdom Division 7.3 nice author solution: fibonacci 7.1 regular polygons bad precision 7.1 7.3 7.4 regular polygons 7.2 7.1 treesets, precision handling tricky cases hard 7.4 Circles UVa - 10005 Packing polygons easy UVa - 10209 Is This Integration ? medium UVa - 10283 The Kissing Circles medium UVa - 10678 The Grazing Cow medium UVa - 1388 medium Graveyard GYM - 100200C Circles medium CF - 342C Cupboard and Balloons medium CF - 617C Watering Flowers easy CF - 140A New Year Table 7.1 7.3 7.4 7.2 circle-circle intersection 7.3 easy kissing circles UVa - 10823 Of Circles and Squares easy brute force UVa - 10947 Bear with me, again.. easy connected components, FW, dsu UVa - 10668 Expanding Rods easy binary search filtered precision problem Quadrilaterals UVA - 11207 The easiest way easy UVa - 142 Mouse Clicks easy rectangles, brute force UVa - 688 Mobile Phone Coverage easy rectangles, brute force UVa - 638 Finding Rectangles easy rectangles, brute force CF - 749B Parallelogram is Back easy UVa - 11639 Guard the Land medium UVa - 12256 Making Quadrilaterals medium CF - 340B medium Maximal Area Quadrilateral 7.3 7.4 7.1 areas, brute force compact solution using triangle area function 3D Objects UVa - 815 Flooded! medium UVa - 737 Gleaming the Cubes medium UVa - 1280 Curvy Little Bottles UVa - 10075 Airlines UVa - 10897 Travelling Distance hard medium easy 7.4 7.3 solid of revolution, binary search, polynomials Needed two EPS because of binary search spheres, FW composite great-circle distance Polygons UVa - 478 Points in Figures: Rectangles, Circles, Triangles easy 7.3 UVa - 11265 The Sultan's Problem easy polygon cut 7.4 UVa - 10065 Useless Tile Packers easy convex hull 7.3 UVa - 109 SCUD Busters easy Topcoder CultureGrowth easy convex hull UVa - 1111 Trash Removal medium convex hull CF - 659D Bicycle Race medium UVa - 811 The Fortified Forest medium convex hull, backtracking, bitmasks CF - 166B Polygons medium point in polygon SPOJ - MPOLYPolygon hard 7.1 very nice, O(1) and O(n) solutions DP Java TLE CS Point in Kgon hard inclusion-exclusion easy areas ↗ experts Measures UVa - 10499 The Land of Justice Geometric Sweep Line Sweep Topcoder BoxUnion easy UVa - 10245 The Closest Pair Problem easy standard UVa - 11378 Bey Battle easy closest pair, Chebyshev distance Topcoder PowerSupply medium CF - 429D Tricky Function medium UVa 12647 Balloon medium UVa - 833 Water Falls medium Topcoder ConvexPolygons hard Circle Sweep UVa 12675 Hide and seek medium Others SPOJ MTRIAREA Maximum Triangle Area medium solvable with inc-exc closest pair line segments, ccw difficulty in modelling the problem as points and required answer is euclidean distance 7.2 weak test cases Ad-hoc Implementation CF - 977A Wrong Subtraction very easy CF - 946A Partition very easy CF - 1041A Heist very easy CF - 1005A Tanya and Stairways very easy CF - 908A New Year and Counting Cards easy CF - 426B Sereja and Mirroring easy CF - 641A Little Artem and Grasshopper easy CF - 669A Little Artem and Presents easy CF - 195A Let's Watch Football easy CF - 436B Om Nom and Spiders easy CF - 182B Vasya's Calendar easy CF - 677C Vanya and Label easy CF - 3C Tic-tac-toe easy CF - 4B Center Alignment easy output formatting CF - 147A Punctuation easy output formatting CF - 63B Settlers' Training easy CF - 705A Hulk easy CF - 62A A Student's Dream easy CF - 71B Progress Bar easy CF - 57A Square Earth? easy CF - 88B Keyboard easy CF - 56B Spoilt Permutation easy CF - 46B T-shirts from Sponsor easy CF - 48A Rock-paper-scissors easy CF - 40A Find Color easy CF - 51A Cheaterius's Problem easy CF - 10A Power Consumption Calculation easy CF - 32B Borze easy CF - 47B Coins easy CF - 8A Train and Peter easy logic nice formula seen number systems UVa - 10082 WERTYU easy GYM - 100015H Hidden Code easy CF - 1016A Death Note easy CF - 1174B Ehab Is an Odd Person easy CF - 382 Arithmetic Progression medium cases handling, sortings CF - 69C Game medium treemaps, brute force CF - 83B Doctor medium sortings, math CF - 93A Frames medium tricky cases CF - 96C Hockey medium strings CF - 433C Ryouko's Memory Note medium sortings, math discussed hardcoding good example for writing small codes sortings GYM - 100200G Ranking medium CF - 863C Yet Another Array Queries Problem medium CF - 34E Collisions hard brute force, physics GYM - 100200D Linear Programming Dual hard parsing backward thinking add to specialists Constructive Algorithms CF - 417C Football easy CF - 331A The Closest Pair easy CF - 63D Dividing Island easy CF - 78B Easter Eggs easy CF - 49C Disposition easy CF - 85A Domino easy CF - 219A Lesha and array splitting easy CF - 1174A Ehab Fails to Be Thanos CF - 590A Median Smoothing medium CF - 663A Rebus medium CF - 59D Team Arrangement medium CF - 82B Sets medium CF - 161B Discounts medium CF - 370C Mittens medium CF - 550E Brackets in Implications medium CF - 949A Zebras medium CF - 1148C Crazy Diamond medium CF - 1174D Ehab and the Expected XOR Problem medium CF - 754C Vladik and chat GYM - 100004B Octagons easy number theory divisibility insights sortings sortings sortings nice editorial solution logic bitmasks, XOring hard assignment problem variant, string parsing solution similar to printing solution in MVC in bipartite graphs, solvable with DP hard reduction important technique easy output formatting Time Waster CF - 151B Phone Numbers CF - 71D Solitaire medium card game, brute force Aces (for speed practice) CF - 686A Free Ice Cream very easy CF - 702A Maximum Increase very easy CF - 688A Opponents easy Random Solutions GYM - 100015IIdentity Checker easy choose x as a multiple of PI Specific Problems and Algorithms UVa - 10017 The Never Ending Towers of Hanoi easy tower of hanoi UVa - 344 easy roman numerals UVa - 11616 Roman Numerals Roman Digititis easy roman numerals UVa - 12397 Roman Numerals easy roman numerals UVa - 759 The Return of the Roman Empire easy roman numerals CF - 61C Capture Valerian easy roman numerals, base number systems UVa - 727 Equation easy expression notation conversion UVa - 120 Stacks of Flapjacks easy pancake sorting, greedy UVa - 1266 Magic Square easy magic square GCJ 09 R2 - CStock Charts medium partially ordered sets, bipartite matching 10.4 link
