Python 代码

nums, ops = [], []
prority = {'-': 0, '+': 0, '*': 1, '/': 1}

char = input()
n = len(char)

def eval():
    op = ops.pop()
    b = nums.pop()
    a = nums.pop()
    if op == "+": a += b
    elif op == "-": a -= b
    elif op == "*": a *= b
    else: a = int(a / b)
    nums.append(a)

i = 0
while i < n:
    if char[i].isdigit():
        num = 0
        while i < n and char[i].isdigit():
            num = num * 10 + int(char[i])
            i += 1
        nums.append(num)
        continue
    elif char[i] == ')':
        while ops[-1] != '(': eval()
        ops.pop()
    elif char[i] == '(': ops.append('(')
    else:
        while ops and ops[-1] != '(' and prority[ops[-1]] >= prority[char[i]]: eval()
        ops.append(char[i])
    i += 1
while ops: eval()
print(nums[-1])