整数反转

1、题目

image-20231218101425194

2、题解

思路1：直接将int类型转换成str类型进行反转

class Solution:
    def reverse(self, x: int) -> int:
        if -10<x<10:
            return x
        str_x = str(x)

        if str_x[0] != "-":
            str_x = str_x[::-1]
            x = int(str_x)
        else:
            str_x = str_x[:0:-1]
            x = int(str_x)
            x = -x
        
        return x if -(2**31)<x<((2**31) -1) else 0
            

思路2：将x的值不断模10，得到的数字加到res中实现反转

class Solution:
    def reverse(self, x: int) -> int:
        y, res = abs(x), 0
        # 则其数值范围为 [−2^31,  2^31 − 1]
        boundry = (1<<31) -1 if x>0 else 1<<31
        while y != 0:
            res = res*10 +y%10
            if res > boundry :
                return 0
            y //=10
        return res if x >0 else -res