📦 1. Array
– Stores elements in a fixed-size sequential list
– Indexed access (0,1,2,...), fast lookup
✅ Use when you need random access
📥 2. Queue (FIFO)
– First-In-First-Out structure
– Elements inserted at rear, removed from front
✅ Useful in scheduling, BFS, etc.
📤 3. Stack (LIFO)
– Last-In-First-Out structure
– Push to add, pop to remove from top
✅ Used in undo, recursion, parsing
🌳 4. Tree
– Hierarchical structure with nodes
– Root at top, child-parent relationships
✅ Useful in XML, file systems, parsing
🔢 5. Matrix (2D Array)
– Grid-like data layout
– Common in image processing, pathfinding
✅ Used in games, simulations, dynamic programming
🔗 6. Linked List
– Nodes linked using pointers
– Each node has value + next reference
✅ Efficient insert/delete, no fixed size
🔑 7. HashMap / Hash Table
– Stores key-value pairs
– Fast access via hash function
✅ Used in caching, dictionaries, lookup
🌲 8. BST (Binary Search Tree)
– Sorted binary tree (left < root < right)
– Enables fast search, insert, delete
✅ Useful in search-heavy operations
🏔️ 9. Heap
– Complete binary tree
– Max-Heap: parent > children (or Min-Heap)
✅ Used in priority queues, heapsort
🔤 10. Trie
– Prefix tree used to store words/strings
– Efficient for autocomplete, dictionary matching
✅ Used in search engines, spell checkers
🔗 11. Graph
– Set of nodes (vertices) and edges
– Directed or undirected, weighted or not
✅ Used in maps, networks, social media
🧩 12. Union-Find (Disjoint Set)
– Helps manage and merge disjoint sets
– Efficient for dynamic connectivity
✅ Used in Kruskal’s algorithm, networks
💡 Why Learn These?
– Build strong problem-solving skills
– Essential for DSA, CP, system design
– Frequently asked in coding interviews
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Top comments (1)
This is a great overview of essential data structures! I’ve been brushing up on these and they’re so critical for improving problem-solving skills. I really like how each one has a clear use case, especially for coding interviews. Understanding these concepts is key, and it’s helpful to see them broken down like this. Definitely saving this for future reference!