LeetCode-in-All
9. Palindrome Number
Easy
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
impl Solution {
pub fn is_palindrome(x: i32) -> bool {
// Negative numbers are not palindromes
if x < 0 {
return false;
}
let mut rev = 0;
let mut local_x = x;
// Reverse the integer
while local_x > 0 {
rev = rev * 10 + local_x % 10;
local_x /= 10;
}
// Check if the reversed integer is the same as the original
rev == x
}
}