11.2 Reverse Integer (Easy)

Reverse digits of an integer.

Example1: x = 123, return 321

Example2: x = -123, return -321

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

The tricky part is we need to check if the result is > Integer.MAX_VALUE.

To achieve this, we need to use long for variable rev.

public class Solution {
    public int reverse(int x) {
           long k=x;
        long rev = 0;             //Use long, so we can check if the result is greater than Integer.MAX_VALUE,
        boolean isNegtive = false;//flag for negative    
        if(k < 0){                //check for negative
            k = 0 - k;
            isNegtive = true;
        }
        System.out.println("k=="+k);
          while (k != 0) {
               rev = rev * 10 + k % 10;
               k = k / 10;
           }


           if(rev > Integer.MAX_VALUE) return 0; //check if result is > Integer.MAX_VALUE
           if (isNegtive)return 0-(int)rev; 
            return (int)rev;
    }
}