全排列dfs

#include <iostream>

#include <vector>
using namespace std;
vector<int> ans;
const int maxn = 1e6 + 10;
int n,vis[maxn];
void dfs(int x)
{
    if(x > n){
        for(auto s : ans)
            cout << s << " ";
        cout << endl;
        return;
    }
    for(int i = 1; i <= n;i++){
        if(!vis[i]){
            ans.push_back(i);
            vis[i] = 1;
            dfs(x + 1);
            vis[i] = 0;
            ans.pop_back();
        }
    }

}
int main()
{
    cin >> n;
    dfs(1);
    return 0;
}