#include <bits/stdc++.h>
using namespace std;
string a;

int main()
{
    cin >> a;
    sort(a.begin(), a.end());
    do
    {
        cout << a;
        cout << endl;
    }while(next_permutation(a.begin(), a.end()));
    return 0;
}

djs解法:

#include <bits/stdc++.h>
using namespace std;
string s;
bool st[10];

vector<char> vec;

void dfs(int u)
{
    if(u == s.size())
    {
        for(auto c: vec) cout << c;
        cout << endl;
        return;
    }
    
    for(int i = 0; i < s.size(); i++)
    {
        if(!st[i])
        {
            st[i] = true;
            vec.push_back(s[i]);
            dfs(u + 1);
            st[i] = false;
            vec.pop_back();
        }
    }
}
int main()
{
    cin >> s;
    sort(s.begin(), s.end());
    dfs(0);
    
    return 0;    
}