2、整数反转 leetcode7

题目描述

description.png

思路：这题用python首先想到的就是转化成数组，用[::-1]来做。但是为了好好学习，还是少用点内置算法。x右移/10，num左移*10，用while

class Solution:
    def reverse(self, x: int) -> int:
        y = abs(x)
        nums = 0
        while(y!=0):
            num = y%10
            nums = nums*10 + num
            y = y//10
            
        if nums>- pow(2,31) and nums < pow(2,31)-1:
            return nums if x > 0 else -nums
        else:
            return 0

另外用python反转的方法：

class Solution:
    def reverse(self, x: int) -> int:
        y,num = abs(x),0
        num = int(str(y)[::-1])
        if num  > -pow(2,31) and num < pow(2,31)-1:  
            return num if x>0 else -num
        else:
            return 0