큐 2

백준 18258

방법1. collections모듈의 deque를 이용

import sys
from collections import deque
n = int(sys.stdin.readline())

queue = deque()
for _ in range(n):
    w = sys.stdin.readline().rstrip().split()
    if w[0]=='push':
        queue.append(w[1])
    elif w[0]=='pop':
        if queue:
            print(queue.popleft())
        else:
            print("-1")
    elif w[0]=='size':
        print(len(queue))
    elif w[0]=='empty':
        if queue:
            print("0")
        else:
            print("1")
    elif w[0]=='front':
        if queue:
            print(queue[0])
        else:
            print("-1")
    elif w[0]=='back':
        if queue:
            print(queue[-1])
        else:
            print("-1")