# 007. Reverse Integer

**<font color=red>难度: Easy</font>**

## 刷题内容

> 原题连接

* https://leetcode.com/problems/reverse-integer/description/

> 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：

```javascript
/**
 * @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
    }
};
```

