Pattern 1
Digit & Math Invariants
Extract (% 10, / 10), state memoization, Floyd's slow/fast cycle pointer.
Pattern 2
Two-Pointer & Frequency
Inward convergence, char freq int[256], palindrome validation, regex rules.
Pattern 3
Linear DSA & Stacks
Pointer reversal for LinkedList, stack adjacent cancellation, queue split.
Pattern 4
2D Grid & Dynamic Prog.
Matrix boundary checks, minimum cost path tabulation dp[i][j], rotation.
Pattern 5
Enterprise OOP Archetype
Static auto-increment IDs, strict validation, abstract/interface polymorphism.