LeetCode - Palindrome

Description

Given an integer x, return true if x is palindrome integer.

An integer is a palindrome when it reads the same backward as forward. For example, 121 is palindrome while 123 is not.

 

Example 1:

Input: x = 121

Output: true

 

Example 2:

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.

 

Example 3:

Input: x = 10

Output: false

Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

 

Example 4:

Input: x = -101

Output: false

 

Constraints:

• -231 <= x <= 231 - 1

 

Follow up: Could you solve it without converting the integer to a string?

 

 

 

Solution

문자열로 변환 없이 Palindrome을 만들어보았습니다.

function isPalindrome(num){
  if(num < 0) return false;
  let pal = 0;
  let n = num
  while(n){
    let last = n%10
    pal = pal*10 + last
    n = Math.floor(n/10)
  }
  return  pal === num;
}