all tasks

Task/Sorting-algorithms-Merge-sort/Scheme/sorting-algorithms-merge-sort.ss

@@ -0,0 +1,23 @@
+(define (merge-sort l gt?)
+  (define (merge left right)
+    (cond
+     ((null? left)
+      right)
+     ((null? right)
+      left)
+     ((gt? (car left) (car right))
+      (cons (car right)
+            (merge left (cdr right))))
+     (else
+      (cons (car left)
+            (merge (cdr left) right)))))
+  (define (take l n)
+    (if (zero? n)
+      (list)
+      (cons (car l)
+            (take (cdr l) (- n 1)))))
+  (let ((half (quotient (length l) 2)))
+    (if (zero? half)
+      l
+      (merge (merge-sort (take      l half) gt?)
+             (merge-sort (list-tail l half) gt?)))))