100+ Problems

The Problem Vault

An interactive, pure-signal database of advanced algorithms and interview patterns. Filter by pattern, difficulty, and language. Learn the core concepts throug.

Title Pattern / Tags Difficulty
Maximize Distance to Closest Person
Medium
Missing Ranges: Array Sweeping
Arrays Sweep Line Intervals
Easy
Next Closest Time: Simulation & Modulo Math
Strings Math Combinatorics
Medium
Graph Traversal (BFS & DFS)
Medium
Meeting Rooms II
Medium
Singly Linked List
Medium
Stack Operations & Min Stack
Medium
Valid Parentheses
Medium
Expressive Words: Run-Length Encoding
Strings Two Pointers Parsing
Medium
Binary Search Trees (BST)
Medium
Kth Largest Element in an Array
Medium
Topological Sort
Medium
Doubly & Circular Lists
Medium
Queue Implementations
Medium
Backspace String Compare
Medium
Find and Replace in String
Medium
Tree Traversals (DFS & BFS)
Medium
Shortest Path (Dijkstra, Bellman-Ford)
Medium
Operations (Reverse, Merge)
Medium
Monotonic Stack
Medium
Lowest Common Ancestor
Medium
Minimum Spanning Tree (MST)
Medium
Fast & Slow Pointers
Medium
Expression Evaluation
Medium
Segment & Fenwick Trees
Medium
Union-Find (Disjoint Set)
Medium
Heaps Practice Problems
Medium
Minimum Cost to Hire K Workers
Medium
Linked Lists Practice Problems
Medium
Sliding Window Maximum
Medium
Trie (Prefix Tree)
Medium
Number of Connected Components
Medium
K Closest Points to Origin
Medium
Merge k Sorted Lists
Medium
Tree Practice Problems
Medium
Stacks & Queues Practice Problems
Medium