归并排序-递归

#include<stdio.h>
#define num 10
int a[num];

void Merging(int a[],int first,int mid,int end)
{
    int i=first,m=mid;
    int j=mid+1,n=end;
    int k=0;
    int temp[num];
    while(i<=m&&j<=n)
    {
        if(a[i]<a[j])temp[k++]=a[i++];
        else temp[k++]=a[j++];
    }
    while(i<=m)
    {
        temp[k++]=a[i++];
    }
    while(j<=n)
    {
        temp[k++]=a[j++];
    }
    for(int i=0;i<k;i++){
        a[first+i]=temp[i];
    }
}
void merge_sort(int a[], int start, int end) {
    int mid = (start+end)/2;
    if(start<end) {
        merge_sort(a, start, mid);
        merge_sort(a, mid+1, end);
        Merging(a, start, mid, end);
    }
}

int main()
{
    printf("Please input a array: ");
    for(int i=0;i<num;i++){
        scanf("%d",&a[i]);
    }
    merge_sort(a,0,num-1);
    printf("After the sort: ");
    for(int i=0;i<num;i++){
        printf("%d ",a[i]);
    }
    return 0;
}