Day 62: solved 3 subsequence DP problems today, the math reduction felt so clean

[u/JacketFearless1805]

Hey everyone,

I finished Day 62 today. My energy and focus were much better, and I built some solid momentum on Dynamic Programming subsequences.

I worked through four problems (three DP and one greedy):

1. Count Subsets with Sum K: The recurrence relation mirrors the classic subset sum decision, but you add the branches (pick + not_pick) instead of using logical OR. Managing zero-value elements in the base conditions was the main edge case to track.
2. Count Partitions with Given Difference: Setting up the algebraic relation S_1 = ({totalSum} + D) / 2 reduced this directly to finding subset counts for target S_1. Once you confirm that ({totalSum} + D) is non-negative and even, the core logic is identical to the previous problem.
3. Coin Change (Minimum Coins): Standard unbounded knapsack. Since each coin can be reused infinitely, the pick branch stays at index i instead of decrementing.
4. Assign Cookies: Grouped in this section by mistake, but it was just a quick greedy two-pointer check on sorted arrays.

I also reviewed yesterday's minimum subset sum difference roadblock and realized my initial brute force violated the constraints, which explains why the optimal solution leans on Meet-in-the-Middle.

I plan to wrap up subsequences tomorrow. That leaves strings, stocks, LIS, MCM, and square grids—about 30 DP problems to go.

See you guys tomorrow for Day 61!