Core tactical patterns that solve hundreds of interview problems: two pointers, sliding window, prefix sums, monotonic stacks, and interval merging.
Prefix sums, 2D prefix sums, Difference Arrays for range updates in O(1), Opposite-Direction Two Pointers, and Dynamic Sliding Windows.
Monotonic Stack for Next Greater / Previous Smaller Element in linear time, Largest Rectangle in Histogram, and Monotonic Queue for sliding windows.
Interval merging and insertion, Top-K elements with min-heaps, fast & slow pointers for linked lists, and bitwise manipulation tricks.