Reverse Integer

Screen Shot 2019-01-02 at 9.31.09 PM.png

今天这个题官方认为很简单哈。
答案：

    class Solution:
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        b = 2 ** 31
        neg_b = -1 * b 
    
        rev = 0 
    
        if x > 0:
            while x != 0:
                digit = x % 10 
                x //= 10 
                rev = rev * 10 + digit 
        else:
            x = abs(x)
            while x != 0:
                digit = x % 10 
                x //= 10 
                rev = rev * 10 + digit
            rev *= -1
    
        if rev > b or rev < neg_b:
            return 0 
        return rev