Merge sort demo

merge_sort.c

#include <stdio.h>
#include <stdlib.h>


static void show(int *nums, int lo, int hi)
{
	int i;
	for (i = lo; i <= hi; i++) {
		printf("%d ", nums[i]);
	}
	printf("\n");
}

/* Merge two sorted array */
static void merge(int *nums, int lo, int mid, int hi)
{
	int i, j, k, len = hi - mid;
	int *tmp = malloc(len * sizeof(int));
	for (i = 0; i < len; i++) {
		tmp[i] = nums[mid + 1 + i];
	}

	i = mid;
	j = len - 1;
	k = hi;
	while (i >= lo && j >= 0) {
		if (nums[i] > tmp[j]) {
			nums[k--] = nums[i--];
		} else {
			nums[k--] = tmp[j--];
		}
	}

	while (j >= 0) {
		nums[k--] = tmp[j--];
	}

	free(tmp);
}

static void merge_sort(int *nums, int lo, int hi)
{
	if (lo >= hi) {
		return;
	}

	int mid = lo + (hi - lo) / 2;
	merge_sort(nums, lo, mid);
	merge_sort(nums, mid + 1, hi);

	merge(nums, lo, mid, hi);
}

int main(int argc, char **argv)
{
	int i, count = argc - 1;
	int *nums = malloc(count * sizeof(int));
	for (i = 0; i < count; i++) {
		nums[i] = atoi(argv[i + 1]);
	}

	merge_sort(nums, 0, count - 1);
	show(nums, 0, count - 1);
	return 0;
}