Master the 14 LeetCode Patterns Cheat Sheet for Coding Interviews

Tired of endless LeetCode grinding? Unlock efficiency with the 14 LeetCode patterns cheat sheet! This guide breaks down the most common problem-solving frameworks – from Two Pointers to Dynamic Programming – so you can confidently tackle coding interviews.

The LeetCode patterns cheat sheet is a curated list of 14 problem-solving strategies that recur across coding challenges. These patterns help you recognize similarities between problems, reducing prep time and boosting accuracy.

Popularized by resources like Tech Interview Handbook, it’s a must-have for structured learning.

1. Why Use the 14 LeetCode Patterns?

1. Speed: Solve problems faster by identifying patterns early.
2. Confidence: Master techniques like Sliding Window or BFS/DFS.
3. Efficiency: Focus on high-impact topics instead of random practice.

List of all Leetcode Problem
1. Easy Problems
2. Medium Problems
3. Hard Problems
4. SQL Problems

2. The 14 Patterns LeetCode Pros Use

Here’s the 14 LeetCode patterns cheat sheet you need:

1. Two Pointers – Use two pointers to traverse arrays/linked lists where you need to find pairs that satisfy specific conditions.
   It is used to find pairs or elements that meet specific criteria.
2. E.g., Two Sum, Palindrome Check
3. Sliding Window – Find subarrays/substrings with specific conditions and also optimize the time complexity.
   Use this pattern when dealing with continuous subarray or substring in coding problems.
   E.g., Maximum Subarray, Longest Substring Without Repeats
4. BFS/DFS – Depth-First Search (DFS) is a traversal technique that explores as far down a branch as possible before backtracking.
   Use the DFS pattern for exploring all paths or branches in graphs or trees.
   
   Breadth-First Search (BFS) is a traversal technique that explores nodes level by level in a tree or graph.
   Use the BFS pattern for finding the shortest paths in unweighted graphs or level-order traversal in trees.
   E.g., Binary Tree Level Order Traversal, Island Count).
5. Dynamic Programming – Involves breaking down problems into smaller subproblems and solving them using a bottom-up or top-down approach.
   Use this pattern for problems with overlapping subproblems and optimal substructure.
   E.g., Climbing Stairs, Knapsack Problem).
6. Binary Search – Efficiently find targets in sorted or rotated arrays.
   Use this pattern when finding a specific element in sorted or rotated arrays.
   E.g., Search in Rotated Array, Find Minimum in Sorted Array).
7. Backtracking – Explores all possible solutions and backtracks when a solution path fails.
   Use this pattern when you need to find all (or some) solutions to a problem that satisfies given constraints.
   E.g., Permutations, Subsets).
8. Greedy Algorithms – Optimize step-by-step choices (e.g., Coin Change, Activity Selection).
9. Heap/Priority Queue – Track max/min elements dynamically
   E.g., Merge K Sorted Lists, Top K Elements).
10. Trie – Prefix tree for string operations
    E.g., Word Search, Autocomplete).
11. Union Find – Manage connected components in graphs
    E.g., Friend Circles, Number of Provinces).
12. Topological Sort – Order nodes in Directed Acyclic Graphs
    E.g., Course Schedule, Task Scheduling).
13. Bit Manipulation – Solve problems using bitwise operations
    E.g., Single Number, Count Set Bits).
14. Prefix Sum – Precompute cumulative sums for range queries. Allow for efficient sum queries on subarrays.
    Use this pattern when you need to perform multiple sum queries on a subarray or need to calculate cumulative sums.
    E.g., Subarray Sum Equals K, Range Sum
15. Monotonic Stack – Maintain ordered stacks for next-greater/smaller problems means in a specific order.
    Use this pattern when required to find the next greater or smaller element
    E.g., Daily Temperatures, Largest Rectangle in Histogram

Master these to decode 80% of coding interview questions! 🚀

3. How to Use the LeetCode Patterns Cheat Sheet

1. Categorize problems: Tag each LeetCode question with its pattern.
2. Practice variations: Solve 3–5 problems per pattern to build muscle memory.
3. Revise weak spots: Use tools for targeted drills.

FAQs

Conclusion

The LeetCode patterns cheat sheet isn’t a shortcut—it’s a smarter way to prep. By mastering these 14 patterns LeetCode experts rely on, you’ll approach interviews strategically, not randomly. Ready to level up?

Grab your cheat sheet and start coding! 🚀

Happy Reading…