习题2.8 输出全排列

习题2.8 输出全排列

#include<bits/stdc++.h>
using namespace std;
int n;
vector<int> arr;
vector<int> aaa;
vector<bool> v;
int num = 0;
void dfs(int temp){

    if (temp == n){
        arr.push_back(num);
        return ;
    }
    
    for (int i = 0; i < n; i ++){
        if (!v[aaa[i]]){
            v[aaa[i]] = true;
            num = num * 10 + aaa[i];
            dfs(temp + 1);
            num = (num - aaa[i]) / 10;
            v[aaa[i]] = false;
        }
    }
}

int main(){
    
    
    cin >> n;
    v.resize(n + 1, false);
    for (int i = 1; i <= n; i ++){
        aaa.push_back(i);
    }
    
    dfs(0);
    for (auto x : arr) cout << x << endl;
    
    return 0;
}