Dynamic Programming, Step by Step

Dynamic programming is where most interview preparation stalls. The obstacle is rarely the code, which is usually short — it is seeing the recurrence, and recognising that a problem has overlapping subproblems in the first place.

These lessons approach DP as a progression rather than a collection of solutions. You start from plain recursion, watch the same subproblem get recomputed, add memoization and see the recomputation disappear, then flip to tabulation and watch the table fill. Working through the classic families — knapsack, sequence, string and tree DP — turns them into recognisable shapes instead of separate problems to memorise.