Palindrome Number Easy 0 attempts
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Palindrome Number

Easy MatrixBFSDFS LeetCode

Given an integer x, determine whether it's a numeric palindrome — that is, whether it reads identically from left to right and right to left.

Input Format
Implement isPalindrome(x). Inputs below show JavaScript function arguments; there is no stdin parsing.
Output Format
Return the result described in the statement.

Sample Input and Output

Example 1 · Run Sample

Input
x = 121
Output
true

Example 2

Input
x = -121
Output
false

Example 3

Input
x = 10
Output
false
Constraints
  • -2^31 <= x <= 2^31 - 1
Test Cases (3)
Case 1
Args: [121] Expected: true
Case 2
Args: [-121] Expected: false
Case 3
Args: [10] Expected: false
Topics
MatrixBFSDFS

Reverse Half

javascript
function isPalindrome(x) {
  if (x < 0 || (x % 10 === 0 && x !== 0)) return false;
  let rev = 0;
  while (x > rev) { rev = rev * 10 + x % 10; x = Math.floor(x / 10); }
  return x === rev || x === Math.floor(rev / 10);
}

Time: O(log n) | Space: O(1)

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JavaScript