题解 | #四则运算#

# 我的解法不能满足特殊情况，比如题目中的-4/(8-6)
# 针对表达式3+2*{1+2*[-4/(8-6)+7]}，我的代码输出是3 2 1 2 4 8 6 - / - 7 + * + * +，这个情况就是错误的，多了一个操作符，对这个-4没法处理，有没有大神指点下啊
'''class Stack():
    def __init__(self):
        self.items = []
        
    def isEmpty(self):
        return self.items == []
    
    def push(self, item):
        self.items.append(item)
    
    def pop(self):
        return self.items.pop()
    
    def peak(self):
        return self.items[len(self.items) -1]
    
    def size(self):
        return len(self.items)
    
inflix = []
tokenList = list(input())
postfixList = []
opStack = Stack()

prec = {}
prec['*'] = 3
prec['/'] = 3
prec['+'] = 2
prec['-'] = 2
prec['('] = 1
prec['{'] = 1  #记录操作符的优先级

for token in tokenList:
    if token in "01234567889":
        postfixList.append(token)
    elif token == '{':
        opStack.push(token)
    elif token == '}':
        topToken = opStack.pop()
        while topToken != '{':
            postfixList.append(topToken)
            topToken = opStack.pop()
    elif token == '(':
        opStack.push(token)
    elif token == ')':
        topToken = opStack.pop()
        while topToken != ')':
            postfixList.append(topToken)
            topToken = opStack.pop()
    else:
        while (not opStack.isEmpty()) and (prec[opStack.peak()] >= prec[token]):
            postfixList.append(opStack.pop())
            opStack.push(token)
            
    while not opStack.isEmpth():
        postfixList.append(opStack.pop())
        
postfixList = ' '.join(postfixList)'''

# 大神的解法，直接用python内置的eval函数
s = input() 
s = s.replace("{", "(") 
s = s.replace("}", ")") 
s = s.replace("[", "(") 
s = s.replace("]", ")") 
print(int(eval(s)))