9. Palindrome Number

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 - 1

# @lc code=start
using LeetCode

function is_palindrome(x::Int)::Bool
    if x < 0
        false
    else
        y = x
        y_reverse = 0
        while y > 0
            y, n = divrem(y, 10)
            y_reverse = y_reverse * 10 + n
        end
        x == y_reverse
    end
end
# @lc code=end

is_palindrome (generic function with 1 method)

This page was generated using DemoCards.jl and Literate.jl.