CS2613/labs/L05/count-odds.rkt
2022-09-27 18:09:00 -03:00

64 lines
1.8 KiB
Racket

#lang racket
(module+ test
(require rackunit))
(define (count-odds lst)
(cond
[(empty? lst) 0]
[(odd? (first lst)) (add1 (count-odds (rest lst)))]
[else (count-odds (rest lst))]))
(module+ test
(check-equal? (count-odds (list 3 2 1 1 2 3 4 5 5 6)) 6))
(define (count-odds2 lst)
(define (helper lst odds)
(cond
[(empty? lst) odds]
[(odd? (first lst)) (helper (rest lst) (add1 odds))]
[else (helper (rest lst) odds)]))
(helper lst 0))
(module+ test
(check-equal? (count-odds2 (list 3 2 1 1 2 3 4 5 5 6)) 6)
(define random-list (build-list 100 (lambda (x) (random 1 100))))
(check-equal? (count-odds random-list) (count-odds2 random-list)))
(define (count-odds3 lst)
(for/fold
([odds 0])
([n lst])
(cond
[(odd? n) (add1 odds)]
[else odds])))
(module+ test
(check-equal? (count-odds3 (list 3 2 1 1 2 3 4 5 5 6)) 6)
(check-equal? (count-odds random-list) (count-odds3 random-list))
(check-equal? (count-odds3 (list 3 2 1 1 2 3 4 5 5 6)) 6))
(define big-list (range 50000000))
(for* ([fun (list count-odds count-odds2 count-odds3)]
[rep '(1 2 3)])
(printf "~a ~a\n" fun rep)
(time (fun big-list)))
;#<procedure:count-odds> 1
;cpu time: 22109 real time: 22390 gc time: 15828
;#<procedure:count-odds> 2
;cpu time: 19578 real time: 19679 gc time: 16250
;#<procedure:count-odds> 3
;cpu time: 18109 real time: 18231 gc time: 14859
;#<procedure:count-odds2> 1
;cpu time: 3125 real time: 3178 gc time: 93
;#<procedure:count-odds2> 2
;cpu time: 2765 real time: 2822 gc time: 31
;#<procedure:count-odds2> 3
;cpu time: 2765 real time: 2798 gc time: 31
;#<procedure:count-odds3> 1
;cpu time: 1000 real time: 1002 gc time: 0
;#<procedure:count-odds3> 2
;cpu time: 1187 real time: 1252 gc time: 15
;#<procedure:count-odds3> 3
;cpu time: 984 real time: 1002 gc time: 0