题解 | #四则运算#

def cal(a, o, b):
    a, b = str(a), str(b)
    u = a + o + b
    return eval(u)


s_ = input()
n = len(s_)

all_list = []
num_list = []
op_list = []

search_digit = True

i = 0
while i < n:
    if s_[i] in "()[]}{":
        all_list.append(s_[i])
        i += 1
        continue
    if not search_digit:
        all_list.append(s_[i])
        i += 1
        search_digit = True
        continue
    num = ""
    if s_[i] == "-":
        num += "-"
        i += 1
    while i < n and s_[i].isdigit():
        num += s_[i]
        i += 1
    all_list.append(int(num))
    search_digit = False


for item in all_list:
    if type(item) == int:
        num_list.append(item)
        continue
    if item in "([{":
        op_list.append(item)
        continue
    if item in ")]}":
        while op_list[-1] not in "([{":
            op = op_list.pop()
            n2 = num_list.pop()
            n1 = num_list.pop()
            num_list.append(cal(n1, op, n2))
        op_list.pop()
        continue

    if item in "-+":
        if len(op_list) == 0 or op_list[-1] in "([{":
            op_list.append(item)
            continue
        while len(op_list) != 0 and op_list[-1] not in "([{":
            op = op_list.pop()
            n2 = num_list.pop()
            n1 = num_list.pop()
            num_list.append(cal(n1, op, n2))
        op_list.append(item)
        continue

    if item in "*/":
        if len(op_list) == 0 or op_list[-1] in "([{-+":
            op_list.append(item)
            continue
        while len(op_list) != 0 and op_list[-1] not in "([{-+":
            op = op_list.pop()
            n2 = num_list.pop()
            n1 = num_list.pop()
            num_list.append(cal(n1, op, n2))
        op_list.append(item)
        continue
    

while len(op_list) != 0:
    op = op_list.pop()
    n2 = num_list.pop()
    n1 = num_list.pop()
    num_list.append(cal(n1, op, n2))

print(int(num_list[0]))