Patterns: (1) Linear DP - Fibonacci, climbing stairs, house robber, (2) Grid DP - unique paths, minimum path sum, (3) String DP - LCS, edit distance, palindrome, (4) Interval DP - matrix chain multiplication, burst balloons, (5) Knapsack - subset sum, coin change, (6) State machine - stock problems with cooldown/fee. Identify pattern, define state, find recurrence.