归并排序

#include <stdio.h>
#include <stdlib.h>
//将有二个有序数列a[first...mid]和a[mid...last]合并。
void mergeArray(int a[], int c[],int left,int mid,int right)
{
    int i, j;
    j=mid+1;
    i=left;
    int m=mid;
    int n=right;
    int k=0;

    while (i <= m && j<= n)
    {
        if (a[i] <= a[j])
            c[k++] = a[i++];
        else
            c[k++] = a[j++];
    }
    while(i <= m)
        c[k++]=a[i++];
    while (j <= n)
        c[k++] = a[j++];
    for(i=0; i<k; i++)
        a[left+i]=c[i];
}
void mergesort(int a[],int p[],int left,int right)
{
    int center;
    if(left<right)
    {

        center=(left+right)/2;
        mergesort(a,p,left,center);
        mergesort(a,p,center+1,right);
        mergeArray(a, p,left, center, right);
    }
}
void MergeSort(int a[],int n)
{
    int *p;
    p=malloc(n*sizeof(int));
    if(p==NULL)
        return;

    mergesort(a,p,0,n-1);
    free(p);
    return;
}

int main(int argc, char *argv[])
{
    int a[13]= {2,4,70,97,127,304,67,77,81,83,99,10,209};
    int b[6]=  {1,2,5,7,9,11};
    int c[19];
    int i;
    MergeSort(a,13);

    for(i=0; i<13; i++)
    {
        printf("%d  ",a[i]);
    }
    printf("\n");

    system("PAUSE");
    return 0;
}

引用

http://blog.youkuaiyun.com/morewindows/article/details/6678165