简单题

#include<iostream>
using namespace std;
int n,a[10];
bool b[10]={0};
void dfs(int x){
    if(x==n){
        for(int i=0;i<n;i++){
            cout<<"    "<<a[i];
        }
        cout<<endl;
        return;
    }
    for(int i=1;i<=n;i++){
        if(!b[i]){
            b[i]=true;
            a[x]=i;
            dfs(x+1);
            b[i]=false;
            a[x]=0;
        }
    }
}
int main(){
    cin>>n;
    dfs(0);
}

#include<bits/stdc++.h>
using namespace std;
int ans[10],n;
bool vis[10];
void dfs(int deep) {
    if (deep == n+1) {
        for (int i = 1;i <= n;i++) {
            cout << "    " << ans[i];
        }
        cout << endl;
        return;
    }
    else {
        for (int i = 1;i <= n;i++) {
            if (vis[i] == true) continue;
            vis[i] = true;
            ans[deep] = i;
            dfs(deep + 1);
            vis[i] = false;
        }
    }
}
int main() {
    cin >> n;
    dfs(1);
    return 0;
}