7. 反转整数

Python实现：

class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        i = 0
        str1=str(x)
        stack = []
        fu = False
        for i in range(len(str1)):
            if str1[i] == '-':
                fu = True
            else:
                stack.insert(0, str1[i])

        result = int(''.join(stack))

        # print(type(result))
        # print(2**31-1)
        # 如果是负数
        if fu:
            if result > 2**31:
                return 0
            else:
                return -result
        else:
            if result > (2**31-1):
                return 0
            else:
                return result

test = Solution()
print(test.reverse(12345))
print(test.reverse(-12345))
print(test.reverse(-123450))