3282. Reach End of Array With Max Score : Deriving optimal solution from Exchange Argument. DP is deadend.
3320. Count The Number of Winning Sequences : Good problem for learning 2D DP. Partitions. Equivalence classes. Negative Indices for Array. Modulo in DP.
3266. Final Array State After K Multiplication Operations II : Divison chops off the number in O(log(n)) steps. Fast Exponentiation. Dynamically changing minimas after each operation. Euclid’s Divison Lemma.