题解 | A+B Problem

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

int main() {
    int n;
    cin>>n;
    vector<char>ch;
    for(int i=0;i<n;i++){
        ch.push_back('A'+i);
    }
    do{
        for(int i=0;i<n;i++){
            if(i>0)cout<<"+";
            cout<<ch[i];
        }
        cout<<" Problem\n";
    }while(next_permutation(ch.begin(),ch.end()));
    return 0;
}