jacob/cs5
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Updated.

Browse Source
This commit is contained in:
Jacob Signorovitch
2025-09-10 12:02:34 -04:00
parent 5be94f117c
commit ce95670d8e
1 changed files with 25 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
welcome-back-to-dr-racket/main.rkt
View File

@@ -1,28 +1,31 @@
;; The first three lines of this file were inserted by DrRacket. They record metadata ;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process. ;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname main) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f))) #reader(lib "htdp-beginner-reader.ss" "lang")((modname main) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
; List of Number -> String ; Number a, Number b, Number c -> String
; Determines whether a list of 3 numbers is ascending or descending. Throws error if neither. ; Determines whether a list of 3 numbers is ascending or descending. Throws error if neither.
(define (scending-how l) (define (scending-how a b c)
(cond [(< (first l) (second l) (third l)) "ascending"] (cond [(< a b c) "ascending"]
[(> (first l) (second l) (third l)) "descending"] [(> a b c) "descending"]
[else (error "too complex")])) [else (error "too complex")]))
(check-expect (scending-how (list 1 2 3)) "ascending") (check-expect (scending-how 1 2 3) "ascending")
(check-expect (scending-how (list 5 4 3)) "descending") (check-expect (scending-how 5 4 3) "descending")
(check-error (scending-how (list 1 0 3))) (check-error (scending-how 1 0 3))
; Number, Number -> Number ; Number a, Number b -> Number
; Finds two positive numbers' greatest common denominator. ; Finds two positive numbers' greatest common denominator.
(define (gcd2 a b) (define (gcd2 a b)
(cond (cond
[(= a 0) b] [(= a 0) b]
[(= b 0) a] [(= b 0) a]
[(= 0 (+ (modulo a 2) (modulo b 2))) (* 2 (gcd2 (/ a 2) (/ b 2)))] [(and (even? a) (even? b))
[(= 0 (modulo b 2)) (gcd2 a (/ b 2))] (* 2 (gcd2 (/ a 2) (/ b 2)))]
[(= 0 (modulo a 2)) (gcd2 (/ a 2) b)] [(even? b) (gcd2 a (/ b 2))]
[else (if (<= a b) (gcd2 a (- b a)) (gcd2 b (- a b)))])) [(even? a) (gcd2 (/ a 2) b)]
[else(if (<= a b)
(gcd2 a (- b a))
(gcd2 b (- a b)))]))
(check-expect (gcd2 0 0) 0) (check-expect (gcd2 0 0) 0)
(check-expect (gcd2 100 0) 100) (check-expect (gcd2 100 0) 100)
@@ -30,3 +33,13 @@
(check-expect (gcd2 10 10) 10) (check-expect (gcd2 10 10) 10)
(check-expect (gcd2 14 7) 7) (check-expect (gcd2 14 7) 7)
(check-expect (gcd2 288 64) 32) (check-expect (gcd2 288 64) 32)
; (gcd2 30 210)
; (* 2 (gcd2 15 105))
; (* 2 (gcd2 15 90))
; (* 2 (gcd2 15 45))
; (* 2 (gcd2 15 30))
; (* 2 (gcd2 15 15))
; (* 2 (gcd2 15 0))
; (* 2 15)
; 30