Palindrome Number & Reverse Integer

Determine whether an integer is a palindrome. Do this without extra space.

分析：把一个数倒过来，然后看两个数是否相同。

public class Solution {
    public boolean isPalindrome(int x) {
        if (x < 0) {
            return false;
        }
        long palindromeX = 0, inputX = x;
        while (x > 0) {
            palindromeX = palindromeX * 10 + (x % 10);
            x = x / 10;
        }
        return palindromeX == inputX;
    }
}

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

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.

public class Solution {
    public int reverse(int x) {
        boolean isPositive = true;
        
        if (x < 0) {
            x = -x;
            isPositive = false;
        }
        
        long reversedValue = 0;
        while (x != 0) {
            reversedValue = reversedValue * 10 + x % 10;
            x /= 10;
        }
        if (Math.abs(reversedValue) > Integer.MAX_VALUE) return 0; 
        
        return isPositive ?  (int)reversedValue : (int)(-reversedValue);
    }
}