题解 | #表达式求值#

import sys

def compute(expr):
    sign = "+"
    ret = [0]
    num = 0
    size = expr.__len__()
    i = 0
    while (i < size):
        if '0' <= expr[i] <= '9':
            num = 10 * num + int(expr[i])
        elif expr[i] == '(':
            left = i
            count = 1
            while (count):
                i += 1
                if expr[i] == '(':
                    count += 1
                elif expr[i] == ')':
                    count -= 1
            num = compute(expr[left+1:i])
        if expr[i] in ('+', '-', '*', '/') or i == size - 1:
            if sign == '+':
                ret.append(num)
            elif sign == '-':
                ret.append(-num)
            elif sign == '*':
                ret[-1] *= num
            elif sign == '/':
                ret[-1] /= num
            sign = expr[i]
            num = 0
        i += 1
    return sum(ret)

for line in sys.stdin.readlines():
    line = line.strip()
    print(compute(line))