题目链接

算法：栈的应用，简化模板题。

对应到y总的模板题 表达式求值.

Pyhton代码

num = []
op = []

def new_eval():
    b = num.pop()
    a = num.pop()
    x = a * n + b * m
    num.append(x)

n,m = map(int,input().split())
li = input()
i = 0
while i < len(li):
    c = li[i]
    if c.isdigit() or c == '-':
        flag = False
        if c == '-':
            flag = True
        x = 0
        if flag:
            j = i + 1
        else:
            j = i
        while j < len(li) and li[j].isdigit():
            x = x * 10 + int(li[j])
            j += 1
        i = j - 1
        if flag:
            x = -x
        num.append(x)
    elif c == '(':
        op.append(c)
    elif c == ')':
        new_eval()
        op.pop()
    i += 1
print(num[0])