Topic	Questions
Arrays	- Find the missing number from a continuous vector of numbers. - Two Missing Numbers. - Find the only non-repeating element where every other element repeats twice. - Modified Two Sum problem. - Next Greater element in a circular array. - Reverse Pairs. - Two pointers question to find (i,j) pairs for a given condition. - Return index where left ≤ element and right ≥ element (prefix/suffix arrays). - Determine minimum daily capacity (X) to complete tasks in Y days (Binary Search). - Find element in a matrix with sorted rows (Binary Search). - Split Array Largest Sum (Binary Search). - Remove K Digits (Greedy). - Maximum Points from Cards (Sliding Window/Prefix Sum).
Strings	- Replace consecutive characters with character and count (e.g., "aaabbb" → "a3b3"). - Longest Substring with All Distinct Characters (Sliding Window). - Longest Palindromic Substring. - Reorganize String (Heap/Greedy). - Valid Parentheses (Stack). - Construct a new string with no adjacent duplicates (Greedy/Heap). - Longest Self-Contained Substring. - Count Binary Substrings. - Group Anagrams (Hashing). - Word Break (DP).
Linked Lists	- Remove consecutive nodes from a linked list with sum zero. - Intersection of Two Linked Lists.
Trees	- Zigzag Level Order Traversal of Binary Tree. - Find Max Path Sum in Binary Tree (follow-up: print path). - Count Nodes with Two Children (recursive & iterative). - Validate Sum Tree. - Distance between two nodes (parent pointers). - Largest BST in a Binary Tree. - Max Sum Level in Binary Tree. - Path Sum I & II. - Print All Possible Arrays that could create a given BST. - House Robber (DP on trees).
Graphs	- Number of Islands (DFS/BFS). - Rotting Oranges (BFS). - Minimum Steps to Reach Cell 9 in Grid (BFS). - Keys and Rooms (DFS/BFS). - Course Schedule II (Topological Sort). - Minimum Knight Moves (BFS).
Dynamic Programming	- Longest Common Subsequence. - House Robber. - Word Break. - Max Path Sum in Binary Tree. - Minimum Steps to Reach Last Index (Jump Game II). - Minimum Time to Finish All Jobs (Binary Search + Greedy/DP).
Hashing	- Three-Page Sequence with Max Count (HashMap). - Group Anagrams (HashMap with sorted keys). - Longest Consecutive Sequence (HashSet). - Insert, Delete, GetRandom O(1) (HashMap + List). - Count Good Review Words (HashMap).
Heaps/Priority Queues	- Top K Frequent Words. - Merge K Sorted Lists (implied in external sorting). - Median from Data Stream (Two Heaps). - Reorganize String (Heap). - K Closest Warehouses (Heap).
Stacks/Queues	- Valid Parentheses. - Next Greater Element in Circular Array. - Design Stack with push, pop, min in O(1) (Auxiliary Stack).
Binary Search	- Square Root of a Number (with precision). - Koko Eating Bananas. - Allocate Minimum Pages. - Split Array Largest Sum. - Search in a Sorted Matrix.
Greedy Algorithms	- Remove K Digits. - Jump Game II. - Minimum Platforms/GPUs Scheduling (Line Sweep/Two Pointers).
Backtracking	- K-th Lexicographical Happy String. - All Possible Arrays for BST (Combinatorics).
Bit Manipulation	- Find Single Element in Sorted Array (XOR or Binary Search).
External Sorting	- Sort a 500MB File with 2MB Heap (External Merge Sort).
System Design/OOP	- Design Stack with min operation. - LRU-like Cache (HashMap + Linked List). - Add & Remove Methods with optimizations (Hash + List).