Decrypt

input/code.cpp: In function 'int main()':
input/code.cpp:59:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < cycle.size(); i++){
                                   ^

#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <utility>
#include <algorithm>
#include <iomanip>
#include <set>

using namespace std;

typedef long long LL;

int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  string f; cin >> f;
  LL k; cin >> k;
  string s; cin >> s;

  set<char> S(f.begin(), f.end());  
  if(S.size() != 26){
    cout << "impossible" << endl;
    return 0;
  }
    
  vector<int> p(26);
  for(int i = 0; i < 26; i++){
    p[i] = f[i] - 'a';
  }
  vector<int> p_inv(26);
  for(int i = 0; i < 26; i++){
    p_inv[p[i]] = i;
  }
  
  //for(auto x : p) cout << x << " "; cout << endl;
  //for(auto x : p_inv) cout << x << " "; cout << endl;
  
  vector<bool> used(26);
  vector<vector<LL> > cycles;
  for(int i = 0; i < 26; i++){
    vector<LL> cycle;
    int cur = i;
    if(used[cur]) continue;
    while(!used[cur]){
      used[cur] = true;
      cycle.push_back(cur);
      cur = p_inv[cur];
    }
    cycles.push_back(cycle);
    //for(auto x : cycle) cout << x << " "; cout << endl;
  }

  vector<int> pk;
  for(int i = 0; i < 26; i++) pk.push_back(i);
  for(auto cycle : cycles){
    LL iters = k % cycle.size();
    for(int i = 0; i < cycle.size(); i++){
      pk[cycle[i]] = cycle[(i+iters) % cycle.size()];
    }
  }
  
  //for(auto x : pk) cout << x << " "; cout << endl;
    
  for(char c : s){
    cout << (char)(pk[c - 'a'] + 'a');
  }
  cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED