There is something deeply satisfying about palindromes. Not the definition — “reads the same forwards and backwards” — but the FEEL of one. Say “racecar” out loud. There is a click at the center, where the e sits like a fulcrum, and the word balances on it.

Now here is a question that sounds tedious but turns out to be beautiful: given a string like aacaabdkacaa, can you find the longest palindrome hiding inside it? You will spot aca almost immediately. But the actual answer is longer than that, and it is hiding in plain sight.