Decrypt

input/code.cpp: In function 'int main()':
input/code.cpp:44:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<D.size(); ++i){
                         ^

#include <iostream>
using namespace std;

int t[26][33];
int r[26], z[26], alk[26];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  string s;
  int k;
  cin >> s >> k;
  for (char c : s) {
    alk[c-'a']++;
  }
  for(int i=0; i<26; ++i) {
    t[s[i]-'a'][0] = i;
    if(alk[s[i]-'a']!=1) t[s[i]-'a'][0]=-1;
  }
  for(int i=0; i<26; ++i) if(alk[i]==0) t[i][0]=-1;
  
  
  for(int i=1; i<32; ++i){
    for(int j=0; j<26; ++j){
      int a=t[j][i-1];
      if(a==-1) {
        t[j][i]=-1;
        continue;
      }
      t[j][i] = t[a][i-1];
    }
  }
  string D;
  cin >> D;
  
 /* for (char c : D) {
    z[c-'a'] = 1;
  }
  for (int i = 0; i < 26; ++i) {
    if (z[i]) for (int j = 0; j < 26; ++j) {
      z[t[j][0]]
    }
  }*/
  string out;
  for(int i=0; i<D.size(); ++i){
    int a=D[i]-'a';
    for(int b=0; (1<<b)<=k; ++b){
      if(k & (1<<b)) a=t[a][b];
      if(a==-1) {
        cout << "impossible\n";
        return 0;
      }
    }
    out.push_back(a+'a');
  }
  cout << out << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED