2020 카카오 인턴십

수식 최대화

🔗 전체 문제 : 수식 최대화

같은 연산자끼리는 앞에 있는 것의 우선순위가 더 높습니다.

1. 숫자와 수식 분리하기
2. 수식의 우선순위 정하기
3. 우선순위에 따른 결과 계산하기

분할 정복 문제

😣 문제를 못풀었다! 다른 분들의 풀이를 보고 복습하기 😣

👀 풀이 1

# 파이썬
from itertools import permutations
import re

def solution(expression):
    expressions = set(re.findall("\D", expression))
    prior = permutations(expressions)
    cand = []

    for op_cand in prior:
        temp = re.compile("(\D)").split('' + expression)
        for exp in op_cand:
            while exp in temp:
                idx = temp.index(exp)
                temp = temp[:idx-1] + [str(eval(''.join(temp[idx-1:idx+2])))] + temp[idx+2:]
        cand.append(abs(int(temp[0])))
    return max(cand)

👀 풀이 2

import re
from itertools import permutations

def solution(expression):
    #1
    op = [x for x in ['*','+','-'] if x in expression]
    op = [list(y) for y in permutations(op)]
    ex = re.split(r'(\D)',expression)

    #2
    a = []
    for x in op:
        _ex = ex[:]
        for y in x:
            while y in _ex:
                tmp = _ex.index(y)
                _ex[tmp-1] = str(eval(_ex[tmp-1]+_ex[tmp]+_ex[tmp+1]))
                _ex = _ex[:tmp]+_ex[tmp+2:]
        a.append(_ex[-1])

    #3
    return max(abs(int(x)) for x in a)

👀 풀이 3

from itertools import permutations
def calc(priority, n, expression):
    if n == 2:
        return str(eval(expression))
    if priority[n] == '*':
        res = eval('*'.join([calc(priority, n + 1, e) for e in expression.split('*')]))
    if priority[n] == '+':
        res = eval('+'.join([calc(priority, n + 1, e) for e in expression.split('+')]))
    if priority[n] == '-':
        res = eval('-'.join([calc(priority, n + 1, e) for e in expression.split('-')]))
    return str(res)


def solution(expression):
    answer = 0
    priorities = (list(permutations(['*','-','+'], 3)))
    for priority in priorities:
        res = int(calc(priority, 0, expression))
        answer = max(answer, abs(res))

    return answer

👀 풀이 4

def solution(expression):
    operations = [('+', '-', '*'),('+', '*', '-'),('-', '+', '*'),('-', '*', '+'),('*', '+', '-'),('*', '-', '+')]
    answer = []
    for op in operations:
        a = op[0]
        b = op[1]
        temp_list = []
        for e in expression.split(a):
            temp = [f"({i})" for i in e.split(b)]
            temp_list.append(f'({b.join(temp)})')
        answer.append(abs(eval(a.join(temp_list))))
    return max(answer)