Link to Problem: https://leetcode.com/problems/valid-palindrome
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.
Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.
Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.
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.
This was my first Two Pointers problem and while it is a LeetCode Easy, I still had some problems with it because I've never done it before.
So of course, I immediately looked up the solution for this. I started with watching NeetCode's explanation of the solution.
While the explanation made sense, I did not have any idea about how to do it in Elixir, so I had to look up the solutions for Elixir.
Some of the solutions looked really complicated that I had to take a second look to see if it was really Elixir code. I eventually found a simpler solution that honestly looks similar to NeetCode's solution in Python.
I have learned some new things with the solution I've seen.
First of all, I mentioned in 49 - Group Anagrams that I discovered that
String.split("") behaves differently from String.grapheme/1.
Well, apparently, String.to_charlist/1 also behaves differently from the other 2 functions I mentioned and I
guess I should just always use that function to split a string into characters moving forward because it's
the one that works as how you would expect it to.
I also learned that using cond is a good flow control mechanism to use when dealing with two pointers.
I'm also noticing a pattern in these Elixir solutions where recursion is used a lot to do loops.