0007._Reverse_Integer

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007. Reverse Integer

难度: Easy

刷题内容

原题连接

内容描述

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

 Input: 123
 Output: 321

Example 2:

 Input: -123
 Output: -321

Example 3:

 Input: 120
 Output: 21

Note:

 Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

解题方案

思路
**- 时间复杂度: O(1)**- 空间复杂度: O(N)**

思路：通过将数字转成数组，然后翻转再转回数字

代码：

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/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
    var num = parseInt(x.toString().split('').reverse().join(''))
    if(num > Math.pow(2, 31)) {
        return 0
    }
    if(x < 0){
        return num*(-1)
    } else {
        return num
    }
};