Created
May 26, 2013 08:41
-
-
Save miyukino/5652105 to your computer and use it in GitHub Desktop.
Scheme: Merge Sort
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| ;; Exp. (merge '(1 3 5 7 8 9 10) '(2 4 6)) ==> (1 2 3 4 5 6 7 8 9 10) | |
| (define (merge L M) | |
| (if (null? L) M | |
| (if (null? M) L | |
| (if (< (car L) (car M)) | |
| (cons (car L) (merge (cdr L) M)) | |
| (cons (car M) (merge (cdr M) L)))))) | |
| ;; split helper functions | |
| (define (odd L) | |
| (if (null? L) '() | |
| (if (null? (cdr L)) (list (car L)) | |
| (cons (car L) (odd (cddr L)))))) | |
| (define (even L) | |
| (if (null? L) '() | |
| (if (null? (cdr L)) '() | |
| (cons (cadr L) (even (cddr L)))))) | |
| ;; Exp. (split '(a b c d e f g h i)) ==> ((a c e g i)(b d f h)) | |
| (define (split L) | |
| (cons (odd L) (cons (even L) `()))) | |
| ;; Exp. (mergesort '(8 1 3 9 6 5 7 2 4 10)) ==> (1 2 3 4 5 6 7 8 9 10) | |
| (define (mergesort L) | |
| (if (null? L) L | |
| (if (null? (cdr L)) L | |
| (merge | |
| (mergesort (car (split L))) | |
| (mergesort (cadr (split L))))))) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment