Master Coding Interview Preparation in 2025 with These 15 Patterns

Preparing for coding interviews can be overwhelming, but learning problem-solving patterns instead of memorizing individual solutions can significantly improve your chances of success.

Why Coding Patterns Matter

Instead of solving thousands of problems, focus on 15 essential coding patterns that can be applied to hundreds of interview questions.

1️⃣ Two Pointers

✅ Key Idea: Use two pointers to traverse arrays or linked lists efficiently.

✅ Example Problems:

• Find the middle element in a linked list.

• Detect cycles in a linked list.

2️⃣ Sliding Window

✅ Key Idea: Maintain a window over part of an array and adjust its size dynamically.

✅ Example Problems:

• Find the longest substring without repeating characters.

• Maximum sum of a subarray of size K.

3️⃣ Fast & Slow Pointers

✅ Key Idea: Use two pointers moving at different speeds to detect cycles.

✅ Example Problems:

• Linked List Cycle detection.

• Find the duplicate number in an array.

4️⃣ Prefix Sum

✅ Key Idea: Precompute cumulative sums for quick range queries.

✅ Example Problems:

• Subarray sum equals K.

• Range sum query.

5️⃣ Monotonic Stack

✅ Key Idea: Maintain a stack that keeps elements in sorted order.

✅ Example Problems:

• Next greater element.

• Largest rectangle in a histogram.

6️⃣ Top ‘K’ Elements

✅ Key Idea: Use heaps or sorting to find the most frequent or largest values.

✅ Example Problems:

• Find the Kth largest element in an array.

• Top K frequent elements.

7️⃣ Modified Binary Search

✅ Key Idea: Apply binary search creatively for custom conditions.

✅ Example Problems:

• Search in a rotated sorted array.

• Find peak element in an array.

8️⃣ Depth-First Search (DFS) & Breadth-First Search (BFS)

✅ Key Idea: Explore tree or graph nodes deeply (DFS) or level by level (BFS).

✅ Example Problems:

• Number of islands.

• Binary tree level order traversal.

9️⃣ Backtracking

✅ Key Idea: Solve problems recursively by trying all solutions and backtracking when needed.

✅ Example Problems:

• Generate all subsets of a set.

• Solve Sudoku puzzles.

🔟 Dynamic Programming

✅ Key Idea: Break problems into subproblems and solve them optimally.

✅ Example Problems:

• Climbing stairs problem.

• Longest increasing subsequence.

Final Thoughts

Mastering these 15 coding patterns will boost your problem-solving skills and help you ace technical interviews at top companies.

🔥 Which pattern do you use the most? Let’s discuss! 🚀