Complete Beginner to Advanced Level Two Pointer, Sliding Window, Fast & Slow Pointers, Cyclic Sort, Merge Intervals, Two Heaps, Top-K Elements, K-Way Merge, Matrix/Island Traversal — A comprehensive guide in Java

Introduction Beyond the foundational algorithms (sorting, searching, graph traversals) lies a set of powerful, reusable problem‑solving patterns. These patterns are the secret weapons of efficient cod