调用next_permutation()函数就完事了

#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
    int a[10];
    int n;
    cin >> n;
    for(int i=1;i<=n;i++) a[i] = i;
    do
    {
        for(int i=1;i<=n;i++) cout<<a[i]<<" ";
        cout<<endl;
    }while(next_permutation(a+1,a+1+n));
}