Palindromic Number

L3 Easy Two Pointers

Concept

A number is a palindrome if it reads the same forwards and backwards. Digits of a negative number can never form a palindrome because of the leading minus sign.

Given an integer x, return true if it reads the same forwards and backwards (ignoring the sign), otherwise false.

Examples

▸ x = 121

→ true

▸ x = -121

→ false

▸ x = 10

→ false

Progressive Hints

Hint 1 · Nudge

The sign isn't part of the reading, so compare digit by digit from both ends.

Hint 2 · Plan

Convert x into a list of its decimal digits. Then compare the first and last digits, moving inward. If any pair differs, return false.

Hint 3 · Approach

digits = decimal digits of x. left = 0, right = last index. While left < right: if digits[left] != digits[right] return false; move left right and right left. Return true.

Output

// Run your code to see the output here.