Practice/Meta/Leetcode 9. Palindrome Number

Leetcode 9. Palindrome Number

CodingMust

Problem

Given an integer, determine whether its digits form a symmetric sequence that reads the same from left to right as it does from right to left.

Negative numbers should always return false since the negative sign only appears at the beginning.

Requirements

1. Return true if the integer's digits are symmetric (palindromic), false otherwise
2. Negative numbers must return false
3. Single-digit numbers should return true
4. Do not convert the integer to a string (challenge yourself to solve it using mathematical operations)

Constraints

• -2^31 <= x <= 2^31 - 1 (standard 32-bit signed integer range)
• Time complexity should be O(log n) where n is the value of the input
• Space complexity should be O(1)

Examples

Example 1:

Input: x = 121 Output: true Explanation: Reading from left to right gives 1-2-1, and reading from right to left also gives 1-2-1

Example 2:

Input: x = -121 Output: false Explanation: From left to right, it reads -121. From right to left, it would be 121-, which is not the same

Example 3:

Input: x = 10 Output: false Explanation: Reading from right to left gives 01, which is different from 10

Example 4:

Input: x = 0 Output: true Explanation: Zero is symmetric