LeetCode Reverse Integer

class Solution:
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        max = pow(2, 31) + 1
        if abs(x) > max:
            return 0
        if x < 0:
            flag = -1
            x = abs(x)
        else:
            flag = 1
        u = 0
        z = []
        while x / 10 != 0:
            y = int(x % 10)
            z.append(y)
            x = int(x / 10)
        u = 0
        p = len(z)
        for dx, val in enumerate(z):
            u += val * pow(10, p - (dx + 1))
            if u > max:
                return 0
        return  u * flag

        rev,s = 0, -1 if x < 0 else 1
        x *= s
        while x != 0:
            rev = rev * 10 + x % 10
            x //= 10
        return 0 if rev > 2147483647 else s * rev

        flag = -1 if x < 0 else 1
        x *= flag
        if x > 2147483647:
            return 0
        res = int(str(abs(x))[::-1])
        if res > 2147483647:
            return 0
        else:
            return res * flag