프로그래머스 lv2 수식최대화

1. 개요

• https://school.programmers.co.kr/learn/courses/30/lessons/77485

2. 풀이

from collections import deque
from itertools import permutations
import re

def solution(expression):
    # operator와 operend 추출
    tokens = re.findall("\d+|\+|\-|\*", expression)
    answer = 0
    
    # 모든 연산자 우선순위를 모두 돌려본다.
    for case in permutations(("+","-","*")):
        nextStack, stack = deque(), deque(t for t in tokens)
        for op in case:
            
            # 연산을 위해 stack을 활용한다.
            # operator와 일치하지않으면 쌓고
            # operator와 일치하면 계산한다.
            while stack:
                token = stack.popleft()
                if token != op:
                    nextStack.append(token)
                else:
                    nextStack.append(calc(nextStack.pop(), stack.popleft(), op))
            nextStack, stack = stack, nextStack
        answer = max(answer, abs(int(stack[0])))
        
    return answer
                    
def calc(left, right, op):
    if op == "+":
        return str(int(left)+int(right))
    elif op == "-":
        return str(int(left)-int(right))
    else:
        return str(int(left)*int(right))