C++(clang++11) 解法, 执行用时: 113ms, 内存消耗: 8556K, 提交时间: 2021-05-06 15:50:18

#include "bits/stdc++.h"
using namespace std;
string s;
vector<int>p[20];
inline int change(char x){
    if(x>='A')return x-'A'+10;
    return x-'0';
}
void dfs(int st,int x,string s1){
    for(int i=st;i<=15;i++){
        auto it=upper_bound(p[i].begin(),p[i].end(),x);
        if(it!=p[i].end()){
            cout<<s1+s[*it]<<endl;
            dfs(i+1,*it,s1+s[*it]);
        }
    }
}
int main()
{
    cin>>s;
    for(int i=0;i<s.size();i++)
        p[change(s[i])].push_back(i);
    dfs(0,-1,"");
    return 0;
}