Coding question patterns for all relevant DSA types: Arrays and Strings 1. Two Pointers: Used for finding pairs or elements that meet specific criteria. 2. Sliding Window: Maintains a subset of elements within a larger dataset. 3. Binary Search: Efficient searching in sorted arrays. 4. Prefix Sum: Precompute cumulative sums for quick range queries. Trees 1. Depth-First Search (DFS): Preorder, inorder, and postorder traversals. 2. Breadth-First Search (BFS): Level-order traversal. 3. Binary Search Tree (BST) operations: Insertion, deletion, and validation. 4. Tree construction: From preorder/inorder or postorder/inorder traversals. Hashtables 1. Frequency counting: Track occurrences of elements. 2. Two Sum pattern: Find pairs with a specific sum. 3. Anagram detection: Compare character frequencies. 4. Caching: Store computed results for quick lookup. Graphs 1. Depth-First Search (DFS): Explore paths deeply before backtracking. 2. Breadth-First Search (BFS): Explore nodes level by level. 3. Topological Sort: Order nodes in a directed acyclic graph. 4. Union Find: Detect cycles and connect components. Stacks 1. Parentheses matching: Validate balanced brackets. 2. Monotonic stack: Maintain increasing/decreasing order for next greater/smaller element problems. 3. Expression evaluation: Evaluate arithmetic expressions. Queues 1. BFS implementation: Level-order traversal in graphs and trees. 2. Task scheduling: Manage order of operations. 3. Sliding window problems: Maintain a window of elements. Heaps 1. Top K Elements Pattern: Find or manipulate the K largest/smallest elements in a collection. 2. Merge K Sorted Pattern: Combine K sorted lists or arrays into a single sorted list. 3. Two Heaps Pattern: Use two heaps to track median or balance elements in a stream. 4. Sliding Window Median Pattern: Calculate median in a sliding window over a stream of numbers. 5. Scheduling Pattern: Manage tasks or intervals using a heap for efficient scheduling. Let me know if I am missing something. I intentionally left out DP (cause no one other than Google cares for it). PS: If you have time left after all this you can look into other common (but rare patterns) like: 1. Tries for word search 2. Backtracking (look at n-Queens problem for reference) 3. Greedy + Binary Search (refer to this problem for pattern) 4. Divide and Conquer (look at merge sort for a template)