归并排序

#include<cstdio>


void Mergearray(int *a, int left, int mid, int right, int *tmp) {
    int i = left;
    int j = mid +1;
    int k = 0;
    int m = mid;
    int n = right;
    //二路归并
    while(i <= m && j <= n) {
        if(a[i] <= a[j]) {
            tmp[k++] = a[i++];
        }
        else {
            tmp[k++] = a[j++];
        }
    }
    //处理子数组中剩余的元素
    while(i <= m) {
        tmp[k++] = a[i++];
    }
    while(j <= n){
        tmp[k++] = a[j++];
    }
    //从临时数组中拷贝到目标数组中
    for(i = 0; i < k; i++)
    {
        a[left+i] = tmp[i];
    }
}


void MergeSort(int *a, int left, int right, int * tmp){
    if(left < right) {
        int mid = left + (right -left)/2;
        //归并排序,使得是左边序列有序
        MergeSort(a, left, mid, tmp);
        //归并排序 使得右边的序列有序
        MergeSort(a, mid+1, right, tmp);
        //合并两个有序序列
        Mergearray(a, left, mid, right, tmp);
    }


}

void printNum(int a[], int n ){
    for(int i =0; i < n; i++)
    {
        printf("%3d", a[i]);
    }
}

int main()
{
    int array[] = {6, 3, 2, 1, 4, 10, 9, 8, 7, 5};
    int b[10];
    MergeSort(array, 0, 9, b);
    printNum(array, 10);
    return  0;
}