Binary Search
Boundaries, predicates, and tricky off-by-ones.
Array
Sliding window, prefix sums, two pointers.
Sorting
Custom comparators and strategy selection.
String
Hashing, windows, parsing, and matching.
Linked List
Pointers, cycles, and in-place tricks.
Stack
Monotonic patterns and expression problems.
Queue
BFS layers, deques, and scheduling.
Tree
DFS, recursion, and invariants.
Heap
Top-K, merges, and greedy scheduling.
Graph
Traversal, connectivity, and modeling.
Matrix
Boundaries, layers, and transforms.
Backtracking & DP
Search trees → states → transitions.
Divide & Conquer
Split/merge, recurrences, and reductions.
Greedy
Proofs, sorting by key, and invariants.
Bit Manipulation
XOR tricks, masks, and counting.
Maths
Number theory basics and constraints.