Nonimperative CS-257: Programming: Scheme!
Spring 2008, Practice Exam
This practice exam gives a sample of the type of questions that will appear on the actual final exam. All questions on the final will be multiple choice. Answer the questions directly on the exam by circling the letter preceding the chosen answer. You may use the white space on the exam for your work. Correct answers receive full credit even with no work shown. Incorrect or alternate answers can sometimes receive full or partial credit based on work shown or comments given. Choose the BEST, SINGLE answer from the options provided. If you feel the need to make comments, then please use printing rather than cursive. Comments that are easily legible are more likely to be read. The actual exam will have more questions than are given here. This practice is intended only as a sample of the type questions, topics and style of questions that will comprise the actual exam. Students may use notes consisting of no more than one 8.5 x 11 inch sheet of paper. Students may use an English or English--other dictionary. 1) What is returned by the call to cdr below? (define p '((a b c) x y z)) (cdr p) a) (x y z) b) (a b c) c) ((a b c)) d) (z) e) z
2) What is returned by the call to cdr below? (define s '(a (d e f))) (cdr (cdr s)) a) cdr: expects argument of type <pair>; given () b) cdr: expects argument of type <pair>; given (f) c) (d e f) d) (e f) e) ()
CS-257: Nonimperative Programming: Scheme!
Spring 2008, Practice Exam
3) Evaluate the scheme expression: (+ 5 (/ (* (+ 10 5) 2 4) 5)) a) 17 1/2 b) 7.5 c) 7.5000000000000000 d) 29 e) 16 1/5
4) What is (eq? (null? '(a)) (null? '(b))) a) #f b) #t c) (#f) d) (#t) e) (#f #f)
5) What is (bitwise-and 6 5) a) 6 b) 5 c) 4 d) 1 e) 0
6) What is (bitwise-xor 6 5) a) 15 b) 13 c) 11 d) 1 e) 0
CS-257: Nonimperative Programming: Scheme!
Spring 2008, Practice Exam
7) Using g, h and k as defined below, what is the value returned by (k 5)? (define g (lambda (a b) (zero? (remainder a b))) ) (define h (lambda (a b) (if (= a b) a (if (g a b) b (h a (+ b 1)) ) ) ) ) (define k (lambda (a) (h a 2))) a) 5 b) 4 c) 3 d) 1 e) 0 8) Using g, h and k as defined above, what is the value returned by (k 91)? a) 91 b) 13 c) 7 d) 1 e) 0 9) What is the output? (let ((a 7) (b 13)) (let ((b 3) (c (+ a b))) (let ((b 5)) (cons a (cons b (cons c ()))) ) ) ) a) (7 b) (7 c) (7 d) (7 e) (7 13 20) 5 20) 3 20) (13 (20))) (3 (20)))
CS-257: Nonimperative Programming: Scheme!
Spring 2008, Practice Exam
10) What how could you make this code run much faster while maintaining its functionality? 1: (define roulette 2: (lambda (myMoney) 3: (define currentBet 1) 4: (define maxBet 10000) 5: (do ((i 0 (+ i 1))) ((>= i 100000000)) 6: (set! myMoney (- myMoney currentBet)) 7: (cond 8: ((< (random) (/ 18 38)) 9: (set! myMoney 10: (+ myMoney (* 2 currentBet))) 11: (set! currentBet 1)) 12: (else 13: (set! currentBet (* 2 currentBet)) 14: (if (> currentBet maxBet) 15: (set! currentBet 1) 16: ) 17: ) 18: ) 19: ) 20: myMoney 21: ) 22: ) 23: (roulette 0) a) Move the definition of currentBet and maxBet outside of the definition roulette. b) Rewrite so that the values of myMoney and currentBet are updated using (let ...) rather than (set! ... ). c) Rewrite so that the values of myMoney and currentBet are updated using (set ...) rather than (set! ... ). d) Rewrite so that roulette takes two parameters: currentBet, and a counter that increments with each call. Then, replace the loop in line 5 with a recersive call to roulette. e) Change line 8 to: ((< (random) (/ 18.0 38.0)) 11) In a single run of the code above, how often is line 13 likely to be executed? a) about 10,000 * 100,000,000 times. about b) 100,000,000 times. c) about 100,000,000 / 2 times. d) about (18 / 38) * 100,000,000 times. e) about (20 / 38) * 100,000,000 times.
CS-257: Nonimperative Programming: Scheme!
Spring 2008, Practice Exam
12) What is the output the following Scheme code? (define foo (lambda x (apply + x) ) ) (foo 3 4 5)
a) procedure foo: expects 1 argument, given 3: 3 4 5 b) procedure application: expected procedure, given: 3; arguments were: 4 5 c) +: expects argument of type <number>; given (3 4 5) d) 3 e) 12 13) In mathematics, the dot product, also known both as the scalar product and v the inner-product, is an operation which takes two vectors a = ( x1 , x 2 , K x n ) , v and b = ( z1 , z 2 , K z n ) over the real numbers and returns a real-valued scalar quantity, s = xi zi
i =1 n
=
x1 z1 + x2 z 2 + K + xn z n .
In Scheme, if a and b are equal length lists of numbers, then the dot product of a and b is: 1: (define inner-product 2: (lambda (a b) 3: ? 4: ) 5: ) Where ? is replaced with: a) (map + (apply * a b)) b) (apply + (map * a b)) c) (map + (map * a b)) d) (apply + (apply * a b)) e) (map + (* a b))
CS-257: Nonimperative Programming: Scheme!
Spring 2008, Practice Exam
14) What is the output the following Scheme code? 1: (define f3 (lambda (myVector1) 2: (define myVector2 3: (apply vector (vector->list myVector1))) 4: (vector-set! myVector2 0 (vector 77 88)) 5: (vector-set! (vector-ref myVector2 1) 0 333) 6: (display myVector1) 7: (display myVector2) (newline) 8: )) 9: (f3 (vector (vector 1 2) (vector 7 8))) a) b) c) d) e) #(#(1 2) #(333 8))#(#(77 88) #(333 8)) #(#(77 88) #(333 8))#(#(77 88) #(333 8)) #(#(1 2) #(7 8))#(#(77 88) #(333 8)) #(#(1 2) #(7 8))#(#(1 2) #(7 8)) #(#(77 88) #(7 8))#(#(77 88) #(333 8))
15) In lines 1 through 9 of the scheme code above, how many times is memory allocated for a new vector object? a) 3 b) 4 c) 6 d) 7 e) 8 16) What would be the output if line 4 were changed to (vector-set! myVector2 0 77)? a) vector-set!: index out of range for vector b) vector-set!: expects type <vector> as 1st argument c) vector-set!: expects type <vector> as 2st argument d) vector-ref: expects type <vector> as 1st argument e) #(#(1 2) #(333 8))#(77 #...