7. Reverse Integer

7. Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.

Assume the environment does not allow you to store 64-bit integers (signed or unsigned).

Example 1:

Input: x = 123
Output: 321

Example 2:

Input: x = -123
Output: -321

Example 3:

Input: x = 120
Output: 21

Example 4:

Input: x = 0
Output: 0

Constraints:

-231 <= x <= 231 - 1

내 풀이

var reverse = function(x) {
    let k;
    x >= 0 ? k=1 : k=-1;
    let num = Number(String(Math.abs(x)).split('').reverse().join(''));
    if(num < -1 * (2**31) || num > 2**31 -1){
        return 0;
    }
    return k * num;
};

Runtime : 88ms Memory : 40.2MB