9. Palindrome Number

Determine whether an integer is a palindrome. An integer is a palindrome when
it reads the same backward as forward.

Example 1:

Input: 121
Output: true

Example 2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-.
Therefore it is not a palindrome.
  • Compare Half

public boolean isPalindrome(int x) {
    if(x < 0 || x > 0 && x % 10 == 0) return false;
    int re = 0;
    while(x > re) {
        re = re * 10 + x % 10;
        x /= 10;
    }
    return re == x || re / 10 == x;
}