#include <iostream>
using namespace std;
const int N = 15;
bool st[N];
int a[N],n;
void dfs(int u){
    if(u == n){
        for(int i = 0 ; i < n ; i++){
            cout << a[i]<< ' ';
        }
        cout << '\n';
    }
    for(int i = 1 ; i <= n ; i++){
        if(!st[i]){
            a[u] = i;
            st[i] = 1;
            dfs(u + 1);
            st[i] = 0;
        }
    }
}
int main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin >> n;
    dfs(0);
    return 0;
}

permutations 搞定

from itertools import permutations
n = int(input())
for i in permutations(range(1, n + 1), n):
    print(*i)

int a[100];
int cnt;
int v[100];
int n;
void dfs()
{
	if(cnt == n)
	{
		for(int i = 1 ; i <= cnt ; i++)
		{
			printf("%d ",a[i]);
		}
		printf("\n");
		return;
	}
	for(int i = 1 ; i <= n ; i++)
	{
		if(!v[i])
		{
			v[i] = 1;
			cnt++;
			a[cnt] = i;
			dfs();
			v[i] = 0;
			cnt--;
		}
	}
}
int main()
{
	scanf("%d", &n);
	dfs();
	return 0;
}