From 8777ff071f7bb37631baa7b6717ad29961e50911 Mon Sep 17 00:00:00 2001 From: "H.J" Date: Wed, 9 Oct 2024 11:36:55 -0400 Subject: sorting by language --- racket/leetcode/lc-43-multiply-strings.rkt | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 racket/leetcode/lc-43-multiply-strings.rkt (limited to 'racket/leetcode/lc-43-multiply-strings.rkt') diff --git a/racket/leetcode/lc-43-multiply-strings.rkt b/racket/leetcode/lc-43-multiply-strings.rkt new file mode 100644 index 0000000..dac8c31 --- /dev/null +++ b/racket/leetcode/lc-43-multiply-strings.rkt @@ -0,0 +1,28 @@ +#lang racket + +(define/contract (char-digit->integer c) + (-> char? integer?) + (- (char->integer c) 48)) + +(define/contract (integer->string-digit n) + (-> integer? string?) + (string (integer->char (+ n 48)))) + +(define/contract (number->string1 n [acc ""]) + (->* (integer?) (string?) string?) + (cond [(and (= n 0) (equal? acc "")) "0"] + [(= n 0) acc] + [else (number->string1 + (quotient n 10) + (string-append (integer->string-digit (remainder n 10)) acc))])) + +(define/contract (multiply num1 num2) + (-> string? string? string?) + (define multiplication-steps + (for/list ([n1 (in-string num1)] + [place1 (in-range (sub1 (string-length num1)) -1 -1)]) + (for/list ([n2 (in-string num2)] + [place2 (in-range (sub1 (string-length num2)) -1 -1)]) + (apply * (append (map char-digit->integer (list n1 n2)) + (list (expt 10 place1) (expt 10 place2))))))) + (number->string1 (apply + (flatten multiplication-steps)))) \ No newline at end of file -- cgit v1.2.3