leetcode

https://leetcode.com/

LEETCODE 15 patterns (https://www.youtube.com/watch?v=DjYZk8nrXVY)

1. Prefix sum

• Use case: Query sum of elements in a subarray
• 303, 525, 560

2. Two pointers

• Use case: palindrom
• 11, 15, 167

3. Sliding Window

• Use case: subarray, substring
• 3, 76, 643

4. Fast and Slow Pointers

• Use case: if a linked list contains cycle?, middle of the linked list
• 141, 202, 287

5. Linked list in-place reversal

• Use case: Reverse a linked list, rearrange the list
• Use three points (prev, curr, next)
• 24, 92, 206

6. Monotonic Stack

• Use case: Next greater/next smaller item in the array
• 84, 496, 739

7. Top k elements

• Use case: K largest/smallest/most frequent
• Using min/max heap
• 215, 347, 373

8. Overlapping Intervals

• Use case: merging interval, interval intersection, insert interval, find minimum meeting rooms
• 56, 57, 435

9. Modified Binary Search

• Use case:
• 33, 153, 240

10. Binary Tree Traversal

• 107, 124, 230, 257

11. DFS

• 113, 133, 210

12. BFS

• 102, 127, 994

13. Matrix Traversal

• 130, 200, 733

14. Backtracking

• 46, 51, 78

15. DP

• 70, 300, 312, 322, 416, 1143

Also referenced Sahil Gaba's linkedin post as follows:

1. BFS and DFS:

• Level Order Traversal: https://lnkd.in/gBgjQPZg
• Number of Islands: https://lnkd.in/gv6pDg_u

2. Dynamic Programming:

• Longest Increasing Subsequence: https://lnkd.in/gdkjpHCv
• Longest Common Subsequence: https://lnkd.in/gn_niUMG

3. Backtracking:

• Combination Sum: https://lnkd.in/g4mUmmqW
• Word Ladder: https://lnkd.in/gMsAtbcR

4. Sliding Window:

• Longest Substring Without Repeating Characters: https://lnkd.in/g9FUYP-u
• Maximum Sum Subarray With Length k: https://lnkd.in/gHdNXSSt

5. Top k Elements:

• k Largest Elements in an Array: https://lnkd.in/g8xWd37F
• k Most Frequent Elements in an Array: https://lnkd.in/g3T6BTqX