7.reverse-integer.kt

/*
 * @lc app=leetcode id=7 lang=kotlin
 *
 * [7] Reverse Integer
 *
 * https://leetcode.com/problems/reverse-integer/description/
 *
 * algorithms
 * Easy (25.24%)
 * Total Accepted:    662.6K
 * Total Submissions: 2.6M
 * Testcase Example:  '123'
 *
 * 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: [−2^31,  2^31 − 1]. For the purpose
 * of this problem, assume that your function returns 0 when the reversed
 * integer overflows.
 * 
 */
class Solution {
    fun reverse(x: Int): Int {
        var res = 0
        var n = x
        while (n != 0) {
            if (Math.abs(res) > Int.MAX_VALUE/10) return 0

            res = res*10 + n % 10
            n /= 10
        }
        return res
    }
}