Assignment 1: CMPT 101/104 Simon Fraser University, School of Computing Science
Due by January 26, 2004
Please refer to the assignment web page for details of assignment preparation.
!!!!!!!!! For problems 2 and 3 below!!!!!!
Please follow the first three steps of the software development method.
1) State the problem,
2) Analyze the problem, define inputs and outputs, and develop a basic algorithm, with a
test plan
3) Refine your algorithm, and present the final refined algorithm.
Include results from all three steps in your submitted solution.
1. (20 points) A salesperson leaves his home every Monday and returns every Friday.
He travels by company car. Each day on the road, the salesperson records the
amount of gasoline put in the car. Given the starting odometer reading (the
odometer reading before he leaves on Monday) and the ending odometer reading
( the odometer reading after he returns home on Friday), design an algorithm to
find the average miles per gallon. A sample data is as follows:
68723 71289 15.75 16.3 10.95 20.65 30.00
Step 1: State the problem
Find the average miles per gallon achieved by the of the salesman’s car.
Step 2 Analyze the problem
The inputs to the problem are
 the odometer reading before and after the salesman used the car
 the number of gallons of gasoline added to the cars gas tank each day
The outputs of the problem are
 The number of miles per gallon of gasoline the car traveled that week
An outline of the algorithm used to derive the solution from the inputs
 Use the Odometer readings to determine the total distance traveled.
 Find the total number of gallons of gasoline used
 Find the average miles per gallon
Special cases or conditions
 we must assume that the amount of gasoline in the car is the same when the
salesman picked up the car and when he dropped off the car.
 Assume the data entered to the algorithm are correct
Test Plan
Use at least two sets of realistic data such as the data set given in the problem
to test the algorithm and program for correctness. Two sets of data will
demonstrate the the algorithm works for more than a single data set.
Develop the algorithm
1. Get startingOdometerReading and endingOdometerReading
2. distanceTraveled = startingOdometerReading – endingOdometerReading;
3. Get gasUsedD1, gasUsedD2, gasUsedD3, gasUsedD4, gasUsedD5
4. totalGasUsed = gasUsedD1 + gasUsedD2 + gasUsedD3 +
gasUsedD4 + gasUsedD5
5.
averageGasPerMile = distanceTraveled / totalGasUsed;
6. Print averageGasPerMile
2. (20 points) Develop an algorithm that takes N+1 coefficients, Ci, of the
polynomial Y  C 0  C1 X 1  C 2 X 2    C N X N , and a value of X as inputs and
evaluates the polynomial to produce the value Y as output.
Step 1: State the problem
Evaluate a polynomial of order N, that is find the value of Y given values of the
coefficients Ci , and a value of the variable X. The polynomial can be
expressed Y  C 0  C1 X 1  C 2 X 2    C N X N
Step 2 Analyze the problem
The inputs to the problem are
 The order of the polynomial N
 the N+1 coefficients of the polynomial Ci
 a value of the variable X
The outputs of the problem are
 The value of the polynomial Y
An outline of the algorithm used to derive the solution from the inputs
For first solution
 Choose a maximum order M for which the algorithm will work
 for order N<M set all coefficients Cn+1 to Cm to zero
 Evaluate the polynomial by using the polynomial equation as given above
for a polynomial of order M.
OR
For second solution
Calculate Y according to
(…((CNX +CN-1)X+CN-2)X+…C1)X+C0
or
 Store the value of CN, in Y
 Repeat the following steps for each N, N=N ... N=1,
a. Multiply Y by X
b. Add coefficient CN-1 to Y
 Add C0 to Y
Special cases or conditions
Soution1
 N>= 0
 Assume the data entered to the algorithm are correct or identify incorrect
input as a special case and include a test for incorrect output in your test
plan and detailed algorithm
 M<N more coefficients than can be evaluated by program
OR
Soution2
 N>= 0
 Assume the data entered to the algorithm are correct or identify incorrect
input as a special case and include a test for incorrect output in your test
plan and detailed algorithm
Test Plan
Soution1
Use 2 or more sets of coefficients with different N, with N<=M to test the
algorithm and program for correctness in ‘normal’ situations
Use 1 or more sets of coefficients with N>M to test the algorithm and program
for correctness in ‘special’ situations
Soution2
Use at least 2 sets of coefficients with different N to test the algorithm and
program for correctness in ‘normal’ situations
Develop the algorithm
Soution1
1. Get N
2. If N>M print error message and stop
3. Get N+1 coefficients Ci
4. Set the coefficient CN+1 … CM to 0
5. Get a value of X
6. Calculate Y  C 0  C1 X 1  C 2 X 2    C M X M
7. Print Y
OR
Soution2
1. Get N
2. Get N+1 coefficients Ci
3. Get a value of X
4. Store the value of CN, in Y
5. Repeat the following steps for each N, N=N ... N=0,
a. Multiply Y by X
b. Add coefficient CN-1 to Y
6. Print Y
3. (10 points) Exercise 6 Given
int n, m, l;
double x, y;
which of the following assignments are valid? If an assignment is not valid, state
the reason. When not noted, assume that each variable is declared.
a. n=m=5;
Valid: An integer value 5 is assigned to an int variable m, the value of
int variable n is then assigned to int variable n
b. m=l=2*n;
Valid: The expression on the righ combines two integers and has an
integer value. The integer value of the expression 2*n is assigned to an
int variable l, the value of int variable l is then assigned to int variable m
c. n=5; m=2+6; n=6/3;
Valid: Each of the expressions on the right have integer values. The
values of each of the expressions of the right are being assigned to
integer variables. The arguments of all operators and assignments are
integers so all operations and assignments are legal.
d. m+n=l;
Invalid: an assignment statement tells us that the value of the
expression on the right is placed in the variable on the left. In this
statement there is an expression on the left. An expression is not
associated with a single location so we do not know where the assign
(put) the value of the expression on the right.
e. x=2*n+5.3;
Valid: The expression on the right is first combining two integers (2*n)
to give and integer. This resulting integer is them combined with a
double. Therefore, the integer result will be converted to a double
(conversion that will not loose information is chosen). The value of the
expressioin on the right will therefore be a double. The assignment
statement is assigning the double value of the expression to a double
variable so the assignment is correct.
f. l+1=n;
Invalid: an assignment statement tells us that the value of the
expression on the right is placed in the variable on the left. In this
statement there is an expression on the left. An expression is not
associated with a single location so we do not know where the assign
(put) the value of the expression on the right.
g. x/y=x*y
Invalid: an assignment statement tells us that the value of the
expression on the right is placed in the variable on the left. In this
statement there is an expression on the left. An expression is not
associated with a single location so we do not know where the assign
(put) the value of the expression on the right.
h. m=n%1;
Valid: The expression on the right combines two integers using the
operator % which is defined on the integer data types. The value of the
expression on the right is an integer an can be assigned to the integer
variable m.
i. n=x%5;
Invalid: The expression on the right is combining an integer and a
double. The operator % is defined on the integer data types but not on
the floating point data types. To evaluate the expression the double
would have to be converted to an int. This conversion will cause a loss of
information. Rather than doing the conversion an error results. The
value of the expression on the right will therefore be invalid and thus the
whole statement will be invalid
j. x=x+5;
Valid: The expression on the right is combining an integer and a double,
therefore the integer will be converted to a double (conversion that will
not loose information is chosen). The value of the expressioin on the
right will therefore be a double. The assignment statement is assigning
the double value of the expression to a double variable so the
assignment is correct.
k. n=3+4.6
Invalid: The expression on the right is combining an integer and a
double, therefore the integer will be converted to a double (conversion
that will not loose information is chosen). The value of the expressioin
on the right will therefore be a double. The assignment statement is
assigning the double value of the expression to a integer variable so the
assignment may cause loss of information and is not allowed.
Alternately, the student may have noticed that the ; is missing. This is an
acceptable alternate reason.
4. (10 points) Write Java statements to accomplish the following.
a. Declare int variables x and y
int x, y;
b. Initialze an int variable x to 10 and a char variable ch to ‘B’
x=10;
ch = ‘B’;
c. Update the value of an int variable x by adding 5 to it
x+=5;
d. Set the value of a double variable z to 25.3
z=25.3;
e. Copy the content of an int variable y into an int variable z
z=y;
f. Swap the contents of the int variables x and y (Declare extra variables if
necessary)
int temp;
temp = x;
x=y;
y=temp;
g. Output the content of a variable x and an expression 2*x+5-y, where x and
y are double variables
System.out.println(x + (2*x+5-y) );
h. Declare a char variable grade and sets the value of grade to ‘A’
char grade=’A’;
i. Declare int variables to store four integers
int a, b, c, d;
j.
Copy the value of a double variable z to the nearest integer into an int
variable x;
z = (int)x;
5. (5 points) Write equivalent compound statements if possible.
a. x = 2 * x;
x += 2;
b. x=x+y-2;
x += y-2;
c. sum=sum + num;
sum += num;
d. z= z * x + 2 * z;
z *= x+2;
e. y=y/(x+5);
y /= x+5;
6. (10 points) Submit a completed assignment cover page to the submission server.
To do this you should follow the following list of instructions:
a. Log in in the assignment lab, download a copy of the cover page from the
course web site. Load the cover page into Microsoft word and fill it in.
b. Save the completed cover page with filename cover.doc (you may want to
print it to use as the cover page for the rest of your assignment)
c. Submit the file cover.doc to the submission server.
If your submission was not received please see me sometime after class on
Friday. I will email those of you whose cover page was not received, to
assure you can submit assignment 2 correctly and on time.
7. (h of the following statement executes. The statements are executed in sequence.
a. (1 point) c = b % a;
The value of a before this statement is 3, a is used as an operator and is
not changed by the execution of this statement
The value of b before this statement is 8, b is used as an operator and is
not changed by the execution of this statement
The value of c is undefined before this statement. The value of the
expression b%a is the remainder of 8/3 or 2. The value of the
expression is assigned to the variable (the location in memory assigned
to the variable) c. After execution of the statement c=2
b. (2 points) c= b/a;
The value of a before this statement is 3, a is used as an operator and is
not changed by the execution of this statement
The value of b before this statement is 8, b is used as an operator and is
not changed by the execution of this statement
The value of c before this statement is 2. The value of the expression b/a
is 8/3 or 2. The value of the expression is assigned to the variable (the
location in memory assigned to the variable) c. After execution of the
statement c=2
c. ( 3 points) c = a++ + - -b;.
The value of a before this statement is 3, this value of a is used as an
operator in the expression on the right, after it is used in the expression
the value of a is incremented (increased) by one. After this line of code is
completely executed a=4.
The value of b before this statement is 8, this value is decremented by 1
to give 7, the value 7 is used as an operator in the expression on the
right. After this line of code is completely executed b=7.
The value of c before this statement is 2. The value of the expression is
a     b  3  7 or 10. The value of the expression is assigned to the
variable (the location in memory assigned to the variable) c. After
execution of the statement c=10
d. ( 2 points) b += a;
a and b are both integers so the assignment statement does not require
conversions
The value of a before this statement is 4, a is used as an operator and is
not changed by the execution of this statement
The value of b before this statement is 7,
The value of a is added to the value of b to give a new value of 11 for b.
e. (2 points) c= -(a=b);
The value of b before this statement is 11
The value of a before this statement is 4,
The value of b is assigned to the variable a (both integer) so the new
value of a is 11
The value of c before this statement is 10 The negative of the contents of
a is assigned to c. c becomes -11.
(5 points) Please print and fill in the “Getting to know you” page. (Page 2 of this
assignment), attach a photo of yourself and attach the “Getting to know you” page
as the last page of the assignment. The “Getting to know you” page will be
removed before your assignment is returned to you.
This one needs no solution!!!
8.