(18258) 큐 2

https://www.acmicpc.net/problem/18258

단계별로 풀어보기

16단계(스택, 큐, 덱 1) 6번째

 

 

 

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

int main() 
{
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  
  queue<int> q;
  int n;
  
  cin >> n;
  
  while(n--){
    string c;
    
    cin >> c;
    
    if(c=="pop"){
      if(!q.empty()){
        cout << q.front() << "\n";
        q.pop();
      }else{
        cout << "-1\n";
      }
    }else if(c=="size"){
      cout << q.size() << "\n";
    }else if(c=="empty"){
      cout << q.empty() << "\n";
    }else if(c=="front"){
      if(!q.empty()){
        cout << q.front() << "\n";
      }else{
        cout << "-1\n";
      }
    }else if(c=="back"){
      if(!q.empty()){
        cout << q.back() << "\n";
      }else{
        cout << "-1\n";
      }
    }else{
      int x;
      
      cin >> x;
      
      q.push(x);
    }
  }
  
  return 0;
}