Backstory: Word break tutorial explains how to use memoization to solve word break problem. Memoization is one of the dynamic programming technique. After applying memoization, the complexity reduces from exponential level to O(n^3).
Why I picked this question: It is intimidating to study Dynamic programming. Actually dynamic programming is not just for questions such as “Longest increasing subsequence”. You many have used it quite often without realizing it. Once you know this “memoization” technique, you would find there are many cases you can apply.