Problem
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.
Solution
/**
* @param {number} x
* @return {number}
*/
var reverse = function(x) {
var INT_MAX = 2147483647;
var INT_MIN = - INT_MAX - 1;
var res = 0;
var num = x;
while (num !== 0) {
res = (res * 10) + (num % 10);
num = num > 0 ? Math.floor(num / 10) : Math.ceil(num / 10);
if (res > INT_MAX || res < INT_MIN) return 0;
}
return res;
};
Explain:
nope.
Complexity:
- Time complexity : O(log(n)).
- Space complexity : O(n).