题目描述

模板题：归并排序

C++代码

#include <bits/stdc++.h>
using namespace std;

const int N = 1e5 + 1;

void merge_sort(int a[], int l, int r){
    if(l >= r)
        return;
    int mid = l + r >> 1;
    merge_sort(a, l, mid);
    merge_sort(a, mid + 1, r);
    int temp[r - l + 1];
    int k = 0, i = l, j = mid + 1;
    while(i <= mid && j <= r){
        if(a[i] <= a[j])
            temp[k++] = a[i++];
        else
            temp[k++] = a[j++];
    }
    while(i <= mid)
        temp[k++] = a[i++];
    while(j <= r)
        temp[k++] = a[j++];
    j = l;
    for(int i = 0; i < k; i++)
        a[j++] = temp[i];
}

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