백준 16953 A -> B

문제 : https://www.acmicpc.net/problem/16953

#include <iostream>
#include <vector>
#include <cmath>
#include <queue>
using namespace std;

int A, B;

void input(){
  cin >> A >> B;
}

void solve(){
  queue<pair<long long, long long>> q;
  q.push({A, 1}); //실제 값, 인덱스
  while(!q.empty()){
    pair<long long, long long> cur = q.front();
    q.pop();
    if(cur.first == B){
      cout << cur.second;
      return;
    }
    if(cur.first * 2 <= B){
      q.push({cur.first * 2, cur.second + 1});
    }
    if(cur.first * 10 + 1 <= B){
      q.push({cur.first * 10 + 1, cur.second + 1});
    }
    
  }
  if(q.empty()){
    cout << "-1";
    return;
  }
  
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  input();
  solve();

  return 0;
}