全排列（next_permutation)

next_permutation函数既可用于非重排列也可用于重排列；

#include <bits/stdc++.h>
#define MAXN 200000+10
#define ll long long
using namespace std;

int a[MAXN];

int main(void)
{
    int n;
    cin >> n;
    for(int i=0; i<n; i++)
    cin >> a[i];
    sort(a, a+n);
    do
    {
        for(int i=0; i<n; i++)
        cout << a[i] << " ";
        cout << endl;
    }while(next_permutation(a, a+n));
    return 0;
}