题解 | #表达式求值#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 返回表达式的值
# @param s string字符串 待计算的表达式
# @return int整型
#
class Solution:
    def solve(self , s: str) -> int:
        # write code here
        n = len(s)
        i = 0
        number = []
        sign = ''
        while i <= n-1:
            
            if s[i] == ')':
                return sum(number), i+1
            
            if s[i] in ['+', '-', '*']:
                sign = s[i]
            if s[i].isdigit() or s[i] == '(':
                if s[i].isdigit():
                    num = int(s[i])
                    while i+1 <= n-1 and s[i+1].isdigit():
                        i += 1
                        num = num * 10 + int(s[i])
                else:
                    num, s_len = self.solve(s[i+1:])
                    i += s_len
                
                if sign == '':
                    number.append(num)
                elif sign == '+':
                    number.append(num)
                elif sign == '-':
                    number.append(-num)
                elif sign == '*':
                    number.append(number.pop() * num)
            i += 1
            
        return sum(number)