Implement function that when given a string, check if string is palindrome.
What does it mean that string is a palindrome?
Example palindrome strings: "", "a", "aba", "aabb", "aaccdccaa".
Not a palindrome string: "abc".
The simplest algorithm works using two pointers (indexes). You set two indexes (i and j) on opposite sides of the string and compare characters on those indexes. If characters are identical you move them towards inside of the string (increment i to move this to the right and decrement j to move this index to the left). You continue this in a loop as long as the characters matches.