Common LeetCode Interview Questions & Patterns
The most common LeetCode interview questions organized by the algorithm pattern they test. Learn the pattern, solve the problems, ace the interview. 217 high-frequency problems tagged by company.
Problems by Pattern
Click any pattern to see its problems with templates and tips.
Sliding Window
27 problems
Two Pointers
51 problems
Binary Search
34 problems
Prefix Sum
9 problems
Hash Map / Set
12 problems
Stack
22 problems
Queue / BFS
10 problems
Heap / Priority Queue
14 problems
Linked List
24 problems
Trees / DFS
18 problems
Graphs
10 problems
Dynamic Programming
26 problems
Greedy
8 problems
Backtracking
14 problems
Trie
5 problems
Union Find
6 problems
Monotonic Stack
7 problems
Topological Sort
5 problems
Bit Manipulation
8 problems
Intervals
4 problems
Matrix
7 problems
Problems by Company
Practice the exact problems each company asks. Filter by your target company.
Top High-Frequency Problems
These problems appear most frequently across FAANG interviews. Start here if you're short on time.
| Problem | Difficulty | Solution | Link |
|---|---|---|---|
| Longest Substring Without Repeating Characters
#String
#Hash Map
#Sliding Window | Medium | Solution | |
| Minimum Window Substring
#String
#Hash Map
#Sliding Window | Hard | Solution | |
| Two Sum II - Input Array Is Sorted
#Array
#Two Pointers
#Binary Search | Medium | Solution | |
| 3Sum
#Array
#Two Pointers
#Sorting | Medium | Solution | |
| Container With Most Water
#Array
#Two Pointers
#Greedy | Medium | Solution | |
| Trapping Rain Water
#Array
#Two Pointers
#Stack | Hard | Solution | |
| Valid Palindrome
#String
#Two Pointers | Easy | Solution | |
| Remove Duplicates from Sorted Array
#Array
#Two Pointers | Easy | Solution | |
| Binary Search
#Array
#Binary Search | Easy | Solution | |
| Search in Rotated Sorted Array
#Array
#Binary Search | Medium | Solution | |
| Find Minimum in Rotated Sorted Array
#Array
#Binary Search | Medium | Solution | |
| Subarray Sum Equals K
#Array
#Hash Map
#Prefix Sum | Medium | Solution | |
| Product of Array Except Self
#Array
#Prefix Product | Medium | Solution | |
| Two Sum
#Array
#Hash Map | Easy | Solution | |
| Group Anagrams
#String
#Hash Map
#Sorting | Medium | Solution | |
| Top K Frequent Elements
#Array
#Hash Map
#Heap | Medium | Solution | |
| Valid Anagram
#String
#Hash Map
#Sorting | Easy | Solution | |
| Longest Consecutive Sequence
#Array
#Hash Set | Medium | Solution | |
| Valid Parentheses
#String
#Stack | Easy | Solution | |
| Min Stack
#Stack
#Design | Medium | Solution | |
| Daily Temperatures
#Array
#Stack
#Monotonic Stack | Medium | Solution | |
| Number of Islands
#Array
#DFS
#BFS | Medium | Solution | |
| Rotting Oranges
#Array
#BFS
#Matrix | Medium | Solution | |
| Binary Tree Level Order Traversal
#Tree
#BFS | Medium | Solution | |
| Kth Largest Element in an Array
#Array
#Heap
#Sorting | Medium | Solution | |
| Find Median from Data Stream
#Two Heaps
#Design
#Sorting | Hard | Solution | |
| Merge K Sorted Lists
#Linked List
#Heap
#Divide and Conquer | Hard | Solution | |
| Reverse Linked List
#Linked List
#Recursion | Easy | Solution | |
| Linked List Cycle
#Linked List
#Two Pointers
#Hash Table | Easy | Solution | |
| Merge Two Sorted Lists
#Linked List
#Recursion | Easy | Solution |
Curated Problem Lists
75
Blind 75
The original curated list by an ex-Meta engineer. The industry standard for FAANG prep.
75
Grind 75
Curated by Tech Interview Handbook. Organized by pattern for better learning progression.
75
Essential 75
Our frequency-based list from 200+ problems. Pattern-first approach for maximum transfer.
Frequently Asked Questions
How many LeetCode problems should I solve for interviews?
Quality beats quantity. Solving 75-150 well-chosen problems across all core patterns is more effective than grinding 500+ random ones. Focus on mastering each pattern with 5-10 representative problems before moving on. The Blind 75 and Grind 75 lists are the most efficient starting points.
What are the most important LeetCode problems for FAANG interviews?
The highest-frequency problems across FAANG companies: Two Sum (LC 1), Valid Parentheses (LC 20), Merge Two Sorted Lists (LC 21), Binary Search (LC 704), Maximum Subarray (LC 53), Climbing Stairs (LC 70), Coin Change (LC 322), Number of Islands (LC 200), Longest Substring Without Repeating Characters (LC 3), and LRU Cache (LC 146). These cover the most common patterns.
How long does it take to prepare for LeetCode interviews?
Most engineers need 8-12 weeks of focused preparation. If you have a solid CS foundation, 6-8 weeks is achievable. The key is consistency — 2 hours daily beats 8 hours on weekends. A pattern-first approach (learn the template, then solve 3-5 problems per pattern) is the most efficient path.
Should I use Python, Java, or C++ for LeetCode interviews?
Use the language you know best — interviewers care about your problem-solving approach, not your language choice. Python is the most popular for interviews because of its concise syntax and built-in data structures. Java and C++ are strong choices for performance-critical reasoning. All three are fully supported by LeetCode.
What is the difference between Blind 75 and NeetCode 150?
Blind 75 is the original curated list of 75 essential problems organized by data structure. NeetCode 150 extends it to 150 problems by adding coverage of Tries, Advanced Graphs, 2D DP, and Bit Manipulation. All 75 Blind 75 problems are included in NeetCode 150. If you have 4-6 weeks, do Blind 75. If you have 8+ weeks, do NeetCode 150.
Which LeetCode problems does Amazon ask most frequently?
Amazon's most frequently asked problems: Two Sum, Valid Parentheses, Merge Intervals, Product of Array Except Self, Top K Frequent Elements, LRU Cache, Word Search, Number of Islands, Binary Tree Level Order Traversal, and Coin Change. Amazon emphasizes arrays, trees, and BFS/DFS patterns. They also heavily test Leadership Principles alongside coding.
Which LeetCode problems does Google ask most frequently?
Google's most frequently asked problems: Merge Intervals, Meeting Rooms II, Product of Array Except Self, Binary Tree Maximum Path Sum, Word Ladder, Alien Dictionary, Trapping Rain Water, Edit Distance, Serialize/Deserialize Binary Tree, and Course Schedule. Google leans heavily on graph problems, dynamic programming, and problems requiring careful edge case handling.