5 problems
Binary Search Practice Problems
Boundary (lower/upper), rotated arrays, and binary search on answer. Practice classic variations and pitfalls.
binary-search
1
4
0
5 problems
Sliding Window Problems
A curated list of classic Sliding Window problems with quick explanations and links to code templates.
sliding-windowmonotonic-deque
1
3
1
4 problems
Monotonic Stack Practice Problems
Next greater element, histogram area, and stack-of-indices techniques that scan once.
monotonic-stack
0
3
1
5 problems
Merge Intervals Practice Problems
Sort-then-merge, sweeping endpoints, and insertion variants for ranges and schedules.
merge-intervalssweep-line
0
5
0
5 problems
Dijkstra's Algorithm Practice Problems
Weighted shortest paths on graphs/grids with priority queue; includes 0-1 BFS alternatives where applicable.
dijkstrashortest-path
0
3
2
5 problems
Union-Find (DSU) Practice Problems
Dynamic connectivity, Kruskal’s MST, and grouping via disjoint-set union with path compression.
union-findmst
0
5
0
4 problems
Segment Tree Practice Problems
Range sum/min/max with point updates; lazy propagation for range updates; coordinate compression as needed.
segment-treerange-queries
0
1
3
3 problems
Fenwick Tree (BIT) Practice Problems
Dynamic prefix sums/frequencies and order statistics using a Binary Indexed Tree.
fenwick-treerange-queries
0
0
3
3 problems
KMP Practice Problems
Prefix function (lps) for exact string matching and related prefix tricks.
kmpstring-algorithms
1
0
2
4 problems
Trie Practice Problems
Prefix trie for dictionary operations and bitwise XOR tricks.
trie
0
3
1
5 problems
Two Pointers — Advanced
Harder two-pointer problems: water trapping, k-sum variants, and linked-list tricks.
two-pointers
1
3
1
5 problems
Graph Shortest Paths
BFS, Dijkstra, 0/1 BFS, and all-pairs approaches in practice.
shortest-pathdijkstra
0
5
0
5 problems
Two Pointers Problems
Classic two-pointer problems on sorted arrays, palindromes, and interval merges.
two-pointerssorting
2
3
0
6 problems
Dynamic Programming Problems
Starter DP problems across fundamentals: 1D, 2D grid, subsequences, and classic recurrences.
dp-1ddp-2d-grid+2 more
1
4
1
How to Use Collections
Each collection focuses on a specific pattern. Start by reading the pattern guide, then work through the problems in order.
Learn Pattern
Study the algorithm pattern guide first
Practice Problems
Solve curated problems progressively
Master Concept
Build intuition through repetition