using System;
using System.Collections.Generic;
using System.Linq;
class MainClass {
static void Main() {
Console.WriteLine($"For sentence 'Kayak' is: {CheckIfSentenceIsPalindrome("Kayak")}");
Console.WriteLine($"For sentence 'Kozak' is: {CheckIfSentenceIsPalindrome("Kozak")}");
Console.WriteLine($"For sentence 'To jest juz za dlugie' is: {CheckIfSentenceIsPalindrome("To jest juz za dlugie")}");
Console.WriteLine($"For sentence 'A man, a plan, a canal, Panama!' is: {CheckIfSentenceIsPalindrome("A man, a plan, a canal, Panama!")}");
Console.WriteLine($"For sentence 'Was it a car or a cat I saw?' is: {CheckIfSentenceIsPalindrome("Was it a car or a cat I saw?")}");
}
// Time O(n) & Space O(1)
private static bool CheckIfSentenceIsPalindrome(string word){
if (word.Length < 1) return true;
int leftSideIndex = 0;
int rightSideIndex = word.Length-1;
while (leftSideIndex < rightSideIndex)
{
while (leftSideIndex < rightSideIndex && !Char.IsLetterOrDigit(word[leftSideIndex])) {
leftSideIndex++;
}
while (leftSideIndex < rightSideIndex && !Char.IsLetterOrDigit(word[rightSideIndex])) {
rightSideIndex--;
}
if (Char.ToLower(word[leftSideIndex]) != Char.ToLower(word[rightSideIndex])) return false;
leftSideIndex++;
rightSideIndex--;
}
return true;
}
}
