Explore paths
Curated tracks that group questions by company, topic, or theme.
Trie
Thirty questions on tries, for prefix matching, autocomplete, and word-search problems.
Backtracking
Fifty questions on backtracking, for generating combinations, permutations, and constraint-satisfaction solutions.
Shortest Path
Twenty-five questions on shortest-path algorithms, including Dijkstra's, Bellman-Ford, and Floyd-Warshall.
Queue
Twenty-five questions on queues, for problems that process elements in the order they arrived.
Topological Sort
Twenty questions on topological sorting, for ordering tasks with dependencies in a directed acyclic graph.
Monotonic Stack
Thirty questions on the monotonic stack pattern, for next-greater/next-smaller and histogram-style problems.
Trees
100 questions on binary trees and binary search trees — traversals, construction, and structural problems.
Prefix Sum
Twenty questions on prefix sums, for answering range-sum and cumulative queries without recomputing from scratch.
BFS
Forty questions focused on breadth-first search, for shortest-path and level-order problems.
Heap
Forty-five questions on heaps and priority queues, for efficiently tracking the smallest or largest elements in a stream.
Dynamic Programming
180 questions spanning the full range of dynamic programming — 1D and 2D DP, interval DP, tree DP, digit DP, and bitmask DP.
Monotonic Queue
Twenty questions on the monotonic queue (deque) pattern, for sliding-window minimum and maximum problems.
Advanced Graph
Thirty-five questions on advanced graph techniques that go beyond traversal — flow, bipartite matching, and more.
DFS
Forty questions focused on depth-first search, for exploring trees and graphs branch by branch.
Linked List
Sixty questions on singly and doubly linked lists — reversal, cycle detection, merging, and in-place manipulation.
Sliding Window
Thirty-five questions on the sliding window technique, for solving subarray and substring problems in linear time.
Graph
120 questions on graphs, from traversal fundamentals to weighted and directed graph algorithms.
Stack
Forty questions on stacks, for parsing, backtracking, and problems that need to undo the most recent operation first.
Arrays
Sixty questions on array manipulation, ordered from easy fundamentals to hard, interview-caliber problems — the foundation every other pattern builds on.
Greedy
Fifty-five questions on greedy algorithms, where the locally optimal choice at each step leads to a globally optimal solution.
Union Find
Thirty-five questions on the union-find (disjoint set) data structure, for connectivity and grouping problems.
Binary Search
Forty-five questions on binary search, from searching sorted arrays to searching directly on the answer space.
Fenwick Tree
Twenty questions on Fenwick trees (binary indexed trees), a compact alternative to segment trees for prefix-sum queries.
Minimum Spanning Tree
Twenty questions on minimum spanning trees, including Kruskal's and Prim's algorithms.
Segment Tree
Twenty-five questions on segment trees, for range queries and updates in logarithmic time.