Algorithms & Data Structures

Binary Search

Search sorted spaces, control interval boundaries, and recognize common binary-search variants.

Sweep Line

Sort interval events, scan them in order, and turn overlap questions into state updates.

Backtracking and DFS

Explore search trees, manage path state, and distinguish reachability DFS from constraint-solving backtracking.

Breadth-First Search (BFS)

Traverse by layers, find shortest unweighted paths, and apply indegree-based topological sorting.

Sliding Window

Maintain a valid contiguous range and replace nested scans with a linear two-pointer pass.

Two Pointers

Coordinate two indices to exploit ordering, maintain ranges, and process linked structures in one pass.

Dynamic Programming

Define states and transitions for overlapping subproblems, from knapsacks to stock and subsequence families.

Greedy

Build a global solution from locally optimal choices when the problem's structure makes those choices safe.

Trees and BSTs

Represent binary trees, choose the right traversal, and exploit binary-search-tree ordering.

Monotonic Stack

Maintain ordered candidates to answer nearest-greater and nearest-smaller questions in linear time.

Stacks and Queues

Use LIFO, FIFO, deques, and priority queues to control processing order and preserve candidates.