/**
 * A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters,
 * it reads the same forward and backward. Alphanumeric characters include letters and numbers.
 *
 * Given a string s, return true if it is a palindrome, or false otherwise.
 *
 *
 *
 * Example 1:
 *
 * Input: s = "A man, a plan, a canal: Panama"
 * Output: true
 * Explanation: "amanaplanacanalpanama" is a palindrome.
 * Example 2:
 *
 * Input: s = "race a car"
 * Output: false
 * Explanation: "raceacar" is not a palindrome.
 * Example 3:
 *
 * Input: s = " "
 * Output: true
 * Explanation: s is an empty string "" after removing non-alphanumeric characters.
 * Since an empty string reads the same forward and backward, it is a palindrome.
 *
 *
 * Constraints:
 *
 * 1 <= s.length <= 2 * 105
 * s consists only of printable ASCII characters.
 * @see <a href="https://leetcode.com/problems/valid-palindrome/">LeetCode</a>
 */
fun isPalindrome(s: String): Boolean {
    val cleanedString = s.filter { it.isLetterOrDigit() }.lowercase()
    if (cleanedString.length <= 1) {
        return true
    }
    var startIndex = 0
    var endIndex = cleanedString.length - 1
    while (startIndex <= endIndex) {
        if (cleanedString[startIndex] == cleanedString[endIndex]) {
            startIndex++
            endIndex--
        } else {
            return false
        }
    }
    return true
}

/**
 * A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters,
 * it reads the same forward and backward. Alphanumeric characters include letters and numbers.
 *
 * Given a string s, return true if it is a palindrome, or false otherwise.
 *
 *
 *
 * Example 1:
 *
 * Input: s = "A man, a plan, a canal: Panama"
 * Output: true
 * Explanation: "amanaplanacanalpanama" is a palindrome.
 * Example 2:
 *
 * Input: s = "race a car"
 * Output: false
 * Explanation: "raceacar" is not a palindrome.
 * Example 3:
 *
 * Input: s = " "
 * Output: true
 * Explanation: s is an empty string "" after removing non-alphanumeric characters.
 * Since an empty string reads the same forward and backward, it is a palindrome.
 *
 *
 * Constraints:
 *
 * 1 <= s.length <= 2 * 105
 * s consists only of printable ASCII characters.
 * @see <a href="https://leetcode.com/problems/valid-palindrome/">LeetCode</a>
 */
fun isPalindrome(s: String): Boolean {
    val cleanedString = s.filter { it.isLetterOrDigit() }.lowercase()
    if (cleanedString.length <= 1) {
        return true
    }
    var startIndex = 0
    var endIndex = cleanedString.length - 1
    while (startIndex <= endIndex) {
        if (cleanedString[startIndex] == cleanedString[endIndex]) {
            startIndex++
            endIndex--
        } else {
            return false
        }
    }
    return true
}
