[LeetCode] Reverse Integer

题意

将数字反过来。没了。

题解

喵蛋为什么要检查数据范围啊！2147483647, 你可知道 Python2 里面 10**100 都是可以直接算的啊！Python2 里面有 sys.maxint，值是 9223372036854775807。

输入、输出不合法，都需要返回 0 。实在太坑。

代码

class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        INT_MAX = 0x7fffffff
        INT_MIN = (-INT_MAX - 1)

        if not INT_MIN < x < INT_MAX:
            return 0

        minus = 1
        ans = 0
        if x < 0:
            minus = -1
        x = abs(x)

        while x > 0:
            ans = ans * 10 + x % 10
            x //= 10
        ans *= minus
        if not INT_MIN < ans < INT_MAX:
            return 0
        return ans

运行

1032 / 1032 test cases passed.
Status: Accepted
Runtime: 76 ms

你是 Python

说道 Python 了，发现了一个非常跪的写法：ans = int(('-' if x < 0 else '') + str(abs(x))[::-1]) 简单粗暴一句话搞定！充分发挥 Python 的优势！

代码

class Solution(object):
    def reverse(self, x):
        INT_MAX = 0x7fffffff
        INT_MIN = (-INT_MAX - 1)
        sign = 1 if x > 0 else -1
        ans = sign * int(str(abs(x))[::-1])

        return ans if INT_MIN <= ans <= INT_MAX else 0

运行

1032 / 1032 test cases passed.
Status: Accepted
Runtime: 76 ms

桩程序

if __name__ == '__main__':
    cases = [
        {'x': 123, 'ans': 321},
        {'x': -123, 'ans': -321},
        {'x': 0, 'ans': 0},
        {'x': 100, 'ans': 1},
        {'x': -100, 'ans': -1},
        {'x': 1534236469, 'ans': 0},
        {'x': 2147483647, 'ans': 0},
        {'x': -2147483648, 'ans': 0},
        {'x': -2147483412, 'ans': -2143847412},
    ]

    for item in cases:
        ans = (Solution()).reverse(x=item['x'])
        print(str(ans == item['ans']) + "\t=>" + str(ans) + ":" + str(item['ans']))