CS 112 - Fall 2012, Lab 01
Haohan Zhu

CS 112 - Fall 2012, Lab 01
Using Piazza
Boston University Slideshow Title Goes Here
 http://www.piazza.com/bu/fall2012/cs112a1
 Any question related to the course
4/12/2020
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CS 112 - Fall 2012, Lab 01 4/12/2020
Using WebSubmit
Boston University Slideshow Title Goes Here
 http://cs-websubmit.bu.edu/main.py?courseid=cs112
 Submit all assignments via WebSubmit
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CS 112 - Fall 2012, Lab 01
Lab Sections and Office Hours
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 Attendence
 Office Hours:
 Tuesday. 5-6:30 p.m.
 Wednesday. 3-4:30 p.m.
 Tutoring Hour:
 http://www.bu.edu/cs/resources/tutoring/
4/12/2020
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CS 112 - Fall 2012, Lab 01 4/12/2020
Stack and Function
Boston University Slideshow Title Goes Here
 Stack: Last In First Out (LIFO)
 Function
F3 F3
Call Return
F2 F2 F2
Call
F1 F1 F1 F1
F2
F1
Return
F1
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CS 112 - Fall 2012, Lab 01 4/12/2020
Recursive Function
Boston University Slideshow Title Goes Here
 Same function, Different variables
F1
F1
F1
Call
Base Case
F1
Call
F1
F1
F1
Return
F1
F1
F1
F1
Return
F1
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CS 112 - Fall 2012, Lab 01 4/12/2020
Recursive Function
Boston University Slideshow Title Goes Here
 Base Case (what to do with trivial inputs)
 Terminating Conditions
 Most logical errors occur at ‘Base Case’
 Not only one base case, maybe many cases
 Recursive Call (how to solve the problem)
 Most difficult part to design a recursive function
 Understand which variables are changing, and which are constant.
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CS 112 - Fall 2012, Lab 01 4/12/2020
Practice
Boston University Slideshow Title Goes Here
 Implementing Exponentiation
 Write a function to recursively compute the function f(x,n) = x^n
 Compare your results with the built ‐ in java function
Math.pow(x, n)
 n is a non-negative integer
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CS 112 - Fall 2012, Lab 01
Practice
Boston University Slideshow Title Goes Here
 Consider f(x,n) = x^(n/2) * x^(n/2)
 What do you need to do if n is odd?
 Count number of recursive calls
 Count time by using: System.nanoTime()
4/12/2020
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