【Leetcode】7：整数反转（Python）

class Solution:
    def reverse(self, x: int) -> int:
        newint=str(x)
        stack=[]
        ret_final=''
        for i in newint:
            stack.append(i)
        ret=[]
        i=len(stack)-1
        while i>-1:
            ret.append(stack[i])
            i-=1
        if ret[-1]=='-':
            ret.pop(-1)
            ret.insert(0,"-")

        if ret[0]=='0':
            ret.pop(0)
        string=''
        for j in ret:
            string=string+j
        if string=='':
            return 0
        if int(string)>2**31-1 or int(string)<-2**31:
            return 0
        return int(string)