Université d’Ottawa Faculté de génie
School of Electrical Engineering and Computer Science
University of Ottawa Faculty of Engineering
École de science informatique et de génie électrique
CSI2120 Programming Paradigms
MIDTERM EXAM
Length of Examination: 75 minutes March 5, 2019, 16:00
Professor: Jochen Lang
Family Name: _________________________________________________ Other Names: _________________________________________________ Student Number: ___________
Signature ____________________________
You are allowed one single-sided, letter-sized, hand-written sheet of notes.
At the end of the exam, when time is up: Stop working and close your exam booklet. Remain silent.
Page 1 of 9
Question
Marks
Out of
1
10
2
4
3
6
4
6
Total
26
2019/03/05 Midterm Exam, CSI 2120 page 2 of 9 ______________________________________________________________________________________________________________
Question 1 [10 marks]
Given the following definitions of the structures shape, triangle and square in Go: package main
import (
“fmt”
“math” )
type Point struct {
X float64
Y float64
}
func Distance(p1 Point, p2 Point) (distance float64) {
distance = math.Sqrt(math.Pow(p1.X-p2.X, 2.0)
+ math.Pow(p1.Y-p2.Y, 2.0))
return }
type Shape interface {
Perimeter() float64
Show() }
type shape struct {
Name string
Vertices []Point
}
type square struct {
shape }
type triangle struct {
shape
}
2019/03/05 Midterm Exam, CSI 2120 page 3 of 9 ______________________________________________________________________________________________________________
a) Write the methods required such that the type triangle will satisfy the interface Shape. Note that Show is to simply print the Name string of triangle.
_________________________________ Show() {
fmt.Println(________________________________________________)
____________________________________________________________________ }
_________________________________ Perimeter() _____________ {
var perimeter float64 = 0.0
for i := 0; i < 3; i++ {
perimeter += Distance(t.Vertices[i], t.Vertices[(i+1)%3])
}
____________________________________________________________________ }
2019/03/05 Midterm Exam, CSI 2120 page 4 of 9 ______________________________________________________________________________________________________________
b) The following code creates 2 squares and 2 triangles.
s1 := NewSquare()
s2 := NewSquare()
t1 := NewTriangle()
t2 := NewTriangle()
Given s1, s2, t1 and t2 and knowing that both types, square and triangle, satisfy the interface Shape,
• initialize an array such that it contains these 4 shapes, and
• compute the sum of all perimeters in a single loop.
____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________
2019/03/05 Midterm Exam, CSI 2120 page 5 of 9 ______________________________________________________________________________________________________________
Question 2 [4 marks]
The main function below creates structures of type Triangle and passes them to the processor function. The triangles are sent over the channel shapeChannel. Once all triangles have been created, the function closes the channel and waits for the processor to finish processing all triangles.
func main() {
shapeChannel := make(chan Triangle, 3)
done := make(chan bool)
go processor(shapeChannel,done)
for j := 1; j <= 10; j++ {
shapeChannel <- NewTriangle(j*j)
}
close(shapeChannel)
<-done }
Complete the processor function below so that it is compatible with the main function above:
func processor(_________________________________________________________) { for {
} }
triangle, more := ______________________________________ if more {
Process(triangle)
} else {
fmt.Println("End of processing")
______________________________________________
return }
2019/03/05 Midterm Exam, CSI 2120 page 6 of 9 ______________________________________________________________________________________________________________
Question 3 [6 marks]
Given the following Prolog program
weather(X,Y) :- snow(X),
rain(X),
Y=snow_and_rain.
weather(X,Y) :- cloudy(X),
rain(X),
Y=cloudy_and_rainy.
weather(X,Y) :- sun(X),
cloudy(X),
Y=mix_of_sun_and_cloud.
weather(X,Y) :- cloudy(X),
Y=gray.
weather(X,Y) :- sun(X),
Y=sunny.
cloudy(monday).
cloudy(tuesday).
cloudy(thursday).
cloudy(friday).
snow(thursday).
sun(wednesday).
sun(friday).
rain(tuesday).
rain(thursday).
a) What is the first solution found by the following query? ?- weather(X,Y).
2019/03/05 Midterm Exam, CSI 2120 page 7 of 9 ______________________________________________________________________________________________________________
b) Give all solutions in order that they are found by Prolog by the following query (and using ; after each answer)?
?- weather(X,gray).
c) Give all solutions in order that they are found by Prolog by the following query (and using ; after each answer)?
?- weather(thursday, Y).
2019/03/05 Midterm Exam, CSI 2120 page 8 of 9 ______________________________________________________________________________________________________________
Question 4 [6 marks]
Given the following Prolog program:
unionList([],B,B).
unionList([E|A],B,D) :-
member(E,B),
unionList(A,B,D).
unionList([E|A],B,[E|D]) :-
\+member(E,B),
unionList(A,B,D).
For example:
?- unionList([1,2,3,7],[3,4,5],L).
L = [1, 2, 7, 3, 4, 5].
But what will be the result if the lists contain duplicate elements?
a) Give the list obtained by the following request:
?- unionList([1,3,5,9,1],[3,4,1,3,1],L).
L = [________________________________________________________________]
b) Give the list obtained by the following request:
?- unionList([1,3,3,6],[2,3,3,3,7],L).
L = [________________________________________________________________]
2019/03/05 Midterm Exam, CSI 2120 page 9 of 9 ______________________________________________________________________________________________________________
Suppose we want to remove duplicates from a list. For example:
?- remove_dup([1,2,3,2,2,3],L).
L = [1, 2, 3]
c) Complete the predicate below correspondingly.
remove_dup([],[]).
remove_dup([E|A],L):- member(E,A), remove_dup(A,L).
remove_dup([E|A],___________________________):-
\+ member(E,A),
remove_dup(__________________________________________________).