ICPC予選2014 D問題

D.cpp

#include <iostream>
#include <map>
#include <string> 
#include <vector>
#include <cstdio>
#include <math.h>
#include <algorithm>
#include <queue>
#include <tuple>
#include <stack>

using namespace std;

bool encrypt(string encrypted, string candidate){
    string used = "";
    for (int i = 0; i < encrypted.size(); ++i){
        char c = candidate[i];
        if (c != 'a' && used.find(c) == string::npos){
            used += c;
            candidate[i] --;
        }
    }
    return encrypted == candidate;
}

int main(int argc, const char * argv[]){
    string str;
    while(cin >> str, str != "#"){
        std::vector<string> decrypt;
        int max = 1 << str.size();

        for (int i = 0; i < max; ++i){
            string rep = str;
            for (int j = 0; j < str.size(); ++j){
                if(i & (1 << j) && str[j] != 'z'){
                    rep[j] = str[j] + 1;
                }
            }
            if(encrypt(str, rep)){
                decrypt.push_back(rep);
            }
        }

        sort(decrypt.begin(), decrypt.end());
        cout << decrypt.size() << endl;
        if (decrypt.size() <= 10){
            for (int i = 0; i < decrypt.size(); ++i){
                cout << decrypt[i] << endl;
            }
        } else {
            for (int i = 0; i < 5; ++i){
                cout << decrypt[i] << endl;
            }
            for (int i = 0; i < 5; ++i){
                cout << decrypt[decrypt.size() - i - 1] << endl;
            }
        }

    }

    return 0;
}