Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Follow up: Could you solve it without converting the integer to a string?
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 - 1struct Solution;
impl Solution {
fn is_palindrome(x: i32) -> bool {
if x < 0 {
return false;
}
let mut reversed = 0;
let mut number = x;
while number > 0 {
reversed = reversed * 10 + number % 10;
number /= 10;
}
x == reversed
// or compare original number as a string with the reversed string
// let x_str = x.abs().to_string();
// x >= 0 && x_str == x_str.chars().rev().collect::<String>()
}
}
#[test]
fn test() {
let x = -123;
let res = false;
assert_eq!(Solution::is_palindrome(x), res);
let x = 12321;
let res = true;
assert_eq!(Solution::is_palindrome(x), res);
}