二刷

C++ 代码

#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
int a[N];
int n;
void merge(int l, int r)
{
    //终止
    if(l >= r) return ;

    int mid = (l + r) >> 1;
    // 分治解决
    merge(l, mid);
    merge(mid + 1, r);

    //下面合并子问题
    int x = r - l + 1;
    int temp[x];         //临时合并函数
    int i = l, j = mid + 1, k = 0;
    while(i <= mid && j <= r) 
    {
        if(a[j] >= a[i])
        {
            temp[k++] = a[i++];
        }
        else temp[k++] = a[j++];
    }
    while(i <= mid) temp[k++] = a[i++];    
    while(j <= r) temp[k++] = a[j++];

    //将临时数组拷贝回原数组
    for(int i = 0, j = l; j <= r; i++, j++)
    {
        a[j] = temp[i];
    }

}
int main()
{
    cin >> n;
    for(int i = 0; i < n; i ++) cin >> a[i];
    merge(0, n - 1);
    for(int i = 0; i < n; i ++) cout << a[i] << " ";
    return 0;
}