September 2017 Update

Task/Sorting-algorithms-Merge-sort/C/sorting-algorithms-merge-sort-1.c

@@ -1,60 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-inline
-void merge(int *left, int l_len, int *right, int r_len, int *out)
-{
-	int i, j, k;
-	for (i = j = k = 0; i < l_len && j < r_len; )
-		out[k++] = left[i] < right[j] ? left[i++] : right[j++];
-
-	while (i < l_len) out[k++] = left[i++];
-	while (j < r_len) out[k++] = right[j++];
-}
-
-/* inner recursion of merge sort */
-void recur(int *buf, int *tmp, int len)
-{
-	int l = len / 2;
-	if (len <= 1) return;
-
-	/* note that buf and tmp are swapped */
-	recur(tmp, buf, l);
-	recur(tmp + l, buf + l, len - l);
-
-	merge(tmp, l, tmp + l, len - l, buf);
-}
-
-/* preparation work before recursion */
-void merge_sort(int *buf, int len)
-{
-	/* call alloc, copy and free only once */
-	int *tmp = malloc(sizeof(int) * len);
-	memcpy(tmp, buf, sizeof(int) * len);
-
-	recur(buf, tmp, len);
-
-	free(tmp);
-}
-
-int main()
-{
-#	define LEN 20
-	int i, x[LEN];
-
-	for (i = 0; i < LEN; i++)
-		x[i] = rand() % LEN;
-
-	puts("before sort:");
-	for (i = 0; i < LEN; i++) printf("%d ", x[i]);
-	putchar('\n');
-
-	merge_sort(x, LEN);
-
-	puts("after sort:");
-	for (i = 0; i < LEN; i++) printf("%d ", x[i]);
-	putchar('\n');
-
-	return 0;
-}

Task/Sorting-algorithms-Merge-sort/C/sorting-algorithms-merge-sort-2.c

@@ -1,70 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-
-typedef struct link_s *link, link_t;
-struct link_s { double v; link next; };
-
-const link_t fnil = { 0./0., &fnil }; // sentinel
-const link const nil = &fnil;
-
-link list_from_array(double *a, int len)
-{
-	link p = nil;
-	while (len--) {
-		link pp = malloc(sizeof(*pp));
-		pp->v = a[len];
-		pp->next = p;
-		p = pp;
-	}
-	return p;
-}
-
-void show_list(link a)
-{
-	for (; a != nil; a = a->next)
-		printf("%g ", a->v);
-	putchar('\n');
-}
-
-link merge(link a, link b)
-{
-	link head = &(link_t){0, nil}, tail = head;
-	while (a != nil && b != nil) {
-		link *p = a->v <= b->v ? &a : &b;
-		tail->next = *p;
-		*p = (*p)->next;
-		tail = tail->next;
-	}
-	tail->next = a != nil ? a : b;
-	return head->next;
-}
-
-link merge_sort(link p)
-{
-	if (p->next == nil) return p;
-
-	link tail = p, mid = p;
-	// Seek to the middle of the list. This is O(n) for list
-	// length, so O(n log n) complexity to overall merge sort
-	// that an array wouldn't have to deal with.
-	while (1) {
-		tail = tail->next->next;
-		if (tail == nil) break;
-		mid = mid->next;
-	}
-
-	tail = mid->next;
-	mid->next = nil;
-
-	return merge(merge_sort(p), merge_sort(tail));
-}
-
-int main(void)
-{
-	double x[] = {5,3,6,1,2,6,2,0,3,5,7,8,2,4,9};
-	link p = list_from_array(x, sizeof(x)/sizeof(x[0]));
-
-	puts("list: "); show_list(p);
-	puts("sort: "); show_list(merge_sort(p));
-	return 0;
-}