What are most common LeetCode patterns?

Question

Design Gurus · Accepted Answer

LeetCode challenges often revolve around certain problem-solving patterns or techniques. Recognizing these patterns can greatly enhance your ability to solve various problems efficiently. Here are some of the most common LeetCode patterns:

1. Sliding Window

Usage: Mainly used for array/string problems.
Purpose: To find a subrange in an array/string, such as a substring or subarray, that meets certain criteria.
Example Problems: Maximum sum subarray of size 'K', smallest subarray with a given sum, longest substring with K distinct characters.

2. Two Pointers

Usage: For arrays, linked lists, strings.
Purpose: Efficiently comparing elements and finding a pair or set of elements that meet specific conditions.
Example Problems: Pair with target sum, remove duplicates, long-pressed name.

3. Fast & Slow Pointers

Usage: Linked lists and arrays.
Purpose: Detecting cycles, finding middle elements, or solving problems requiring a certain form of traversal.
Example Problems: Start of LinkedList cycle, happy number, middle of the LinkedList.

4. Two Heaps

Usage: Problems involving a set of elements divided into two parts to find a median, or for scheduling and interval problems.
Purpose: To manage two sets of numbers where one set is always greater or smaller than the other.
Example Problems: Find median from data stream, maximize capital, minimum number of refueling stops.

5. Merge Intervals

Usage: Intervals, ranges, or time slots.
Purpose: To merge overlapping intervals and sort intervals.
Example Problems: Merge intervals, insert interval, employee free time.

What are most common LeetCode patterns?

1. Sliding Window

2. Two Pointers

3. Fast & Slow Pointers

4. Two Heaps

5. Merge Intervals

6. Cyclic Sort

7. In-place Reversal of a LinkedList

8. Tree Breadth-First Search (BFS)

9. Tree Depth-First Search (DFS)

10. Topological Sort (Graph)

11. Subset/Backtracking

12. Dynamic Programming

Conclusion