归并排序

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

void Merge(int array[], int start, int middle, int end)
{
	int i, j, k, n1, n2;
	
	n1 = middle - start + 1;              
	n2 = end - middle; 

	int *L = (int *)malloc(n1 * sizeof(int));
	int *R = (int *)malloc(n2 * sizeof(int));

	for (i = 0, k = start; i < n1; i++, k++)
	{
		L[i] = array[k];
	}

	for (i = 0, k = middle + 1; i < n2; i++, k++)
	{
		R[i] = array[k];
	}

	for (k = start, i = 0, j = 0; i < n1 && j < n2; k++)
	{
		if (L[i] < R[j])
		{
			array[k] = L[i];
			i++;
		}
		else
		{
			array[k] = R[j];
			j++;
		}
	}

	if (i < n1)
	{
		for (j = i; j < n1; j++, k++)
		{
			array[k] = L[j];
		}
	}

	if (j < n2)
	{
		for (i = j; i < n2; i++, k++)
		{
			array[k] = R[i];
		}
	}
}

void MergeSort(int array[], int start, int end)
{
	int middle;
	int i;

	if (start < end)
	{
		middle = (start + end) / 2;
		
		MergeSort(array, start, middle);
		MergeSort(array, middle + 1, end);
		Merge(array, start, middle, end);
	}
}

int main()
{
	int i = 0;
	int a[] = {49, 38, 65, 97, 76, 13, 27};
	int length = sizeof(a) / sizeof(a[0]);

	MergeSort(a, 0, length -1);

	for (i = 0 ; i < length; i++)
	{
		printf("%d ", a[i]);
	}
	printf("\n");

	return 0;
}