9. Palindrome Number

Given an integer x, return true if x is a palindrome, and false otherwise.

palindrome: An integer is a palindrome when it reads the same forward and backward.

Input: x = 121
Output: true

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

Input: x = 10
Output: false

Solution

function isPalindrome(x: number): boolean {
  if (x < 0) return false;
  if (x < 10) return true;
  const stringNum = x.toString();
  let left = 0;
  let right = stringNum.length - 1;
  while (right > left) {
    if (stringNum[left] !== stringNum[right]) return false;
    left++;
    right--;
  }  
  return true;
}