Buddha's foot before examination: the second play of leetcode

subject ：

answer ：

    def reverse(x):
        ans=""
        if x < -(2**31) or x > (2**31)-1:
            return 0
        if x > 0:
            x = str(x)
            for i in range(1,len(x)+1):
                ans+=x[-i]
        elif x == 0:
            ans = 0
        else:
            x = str(x)[1:]
            ans = "-"
            for i in range(1,len(x)+1):
                ans+=x[-i]
        ans = int(ans)
        if ans < -(2**31) or ans > (2**31)-1:
            ans = 0
        return ans