To excel in coding interviews and effectively solve problems on platforms like LeetCode, it’s essential to master key data structures and algorithms. Below is a curated list of the most important concepts, each with a brief description and representative LeetCode problems.
1. 📦 Arrays and Strings
Operations: Traversal, insertion, deletion, searching, sorting
Common Problems:
- Two Sum (LeetCode #1)
- Longest Substring Without Repeating Characters (LeetCode #3)
- Find the Duplicate Number (LeetCode #287)
2. 🔗 Linked Lists
Operations: Insertion, deletion, reversal, node manipulation
Common Problems:
- Reverse Linked List (LeetCode #206)
- Add Two Numbers (LeetCode #2)
- Merge Two Sorted Lists (LeetCode #21)
3. 🥞 Stacks and Queues
Operations: Push, pop, peek, enqueue, dequeue
Common Problems:
- Valid Parentheses (LeetCode #20)
- Min Stack (LeetCode #155)
- Implement Queue using Stacks (LeetCode #232)
4. 🌲 Trees
Operations: Traversals (in-order, pre-order, post-order), insertion, deletion
Common Problems:
- Binary Tree Inorder Traversal (LeetCode #94)
- Maximum Depth of Binary Tree (LeetCode #104)
- Symmetric Tree (LeetCode #101)
5. 🌐 Graphs
Operations: DFS, BFS, shortest path, cycle detection
Common Problems:
- Number of Islands (LeetCode #200)
- Clone Graph (LeetCode #133)
- Course Schedule (LeetCode #207)
6. 🧠 Hash Tables
Operations: Insertion, lookup, deletion
Common Problems:
- Two Sum (LeetCode #1)
- Group Anagrams (LeetCode #49)
- Longest Consecutive Sequence (LeetCode #128)
7. 🛞 Heaps (Priority Queues)
Operations: Insert, extract min/max, peek
Common Problems:
- Top K Frequent Elements (LeetCode #347)
- Merge k Sorted Lists (LeetCode #23)
- Kth Largest Element in an Array (LeetCode #215)
8. 🔍 Sorting and Searching
Algorithms: Quick Sort, Merge Sort, Binary Search
Common Problems:
- Binary Search (LeetCode #704)
- Merge Intervals (LeetCode #56)
- Search in Rotated Sorted Array (LeetCode #33)
9. 📈 Dynamic Programming
Techniques: Memoization, Tabulation
Common Problems:
- Climbing Stairs (LeetCode #70)
- Longest Increasing Subsequence (LeetCode #300)
- Partition Equal Subset Sum (LeetCode #416)
10. 🔄 Backtracking
Techniques: Recursive exploration, pruning
Common Problems:
- Permutations (LeetCode #46)
- Combination Sum (LeetCode #39)
- N-Queens (LeetCode #51)
11. 🧭 Graph Algorithms (Advanced)
Algorithms: Dijkstra’s, Bellman-Ford, Floyd-Warshall
Common Problems:
- Minimum Spanning Tree (LeetCode #1135)
- Network Delay Time (LeetCode #743)
📝 Final Thoughts
Mastering these data structures and algorithmic strategies — and practicing through LeetCode — will significantly boost your coding interview performance and problem-solving confidence.