Learn These Fundamental Data Structures to Solve 90% of Problems
1. Arrays
Concepts: Static or dynamic contiguous memory storage.
Use Cases: Iteration, sorting, searching, prefix sums, sliding windows.

2. Strings
Concepts: A specialized array of characters.
Use Cases: Text processing, pattern matching, hashing.

3. Linked Lists
Concepts: Nodes connected via pointers.
Types: Singly, Doubly, Circular.

4. Stacks and Queues
Core Operations: Push, pop, enqueue, dequeue.
Variants: Priority Queue, Deque.
Use Cases:
  -Stacks: Expression evaluation, Next Greater Element.
  -Queues: BFS, task scheduling.

5. Trees and Graphs
Trees: Hierarchical data (binary trees, binary search trees, tries).
Graphs: Networks of nodes (BFS, DFS, shortest paths, MST).
Use Cases:
  -Trees: Range queries, structured data storage.
  -Graphs: Navigation, social networks, dependencies.