AcWing 787. 归并排序

• 一、题目链接
• 二、题目分析
• • （一）算法标签
  • （二）解题思路
• 三、AC代码
• 四、其它题解

一、题目链接

AcWing 787. 归并排序

二、题目分析

（一）算法标签

归并排序

（二）解题思路

三、AC代码

解法一:

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1e5 + 10;

int a[N];
int tmp[N];

void merge_sort(int l, int r)
{
    if (l >= r) return;
    int mid = l + r >> 1;
    
    int i = l, j = mid + 1, k = 1;
    merge_sort(l, mid), merge_sort(mid + 1, r);
    while (i <= mid && j <= r)
    {
        if (a[i] <= a[j])
            tmp[k ++ ] = a[i ++ ];
        else
            tmp[k ++ ] = a[j ++ ];
    }
    while (i <= mid) tmp[k ++ ] = a[i ++ ];
    while (j <= r) tmp[k ++ ] = a[j ++ ];
    for (int i = l, k = 1; i <= r; i ++, k ++ ) a[i] = tmp[k];
}
int main()
{
    int n;
    cin >> n;
    
    for (int i = 1; i <= n; i ++ ) scanf("%d", &a[i]);
    
    merge_sort(1, n);
    
    for (int i = 1; i <= n; i ++ ) printf("%d ", a[i]);
    return 0;
}

四、其它题解

AcWing 787. 归并排序 1
AcWing 787. 归并排序 2