1. Segment Tree, Fenwick Tree

Question Time
315. Count of Smaller Numbers After Self <2025-06-19 周四>
3161. Block Placement Queries <2025-06-19 周四>
307. Range Sum Query - Mutable <2025-06-19 周四>

3. Two Pointers

Question Time
42. Trapping Rain Water <2025-06-19 周四>
407. Trapping Rain Water II <2025-06-19 周四>

4. Prefix/Suffix Sum

Question Time
2845. Count of Interesting Subarrays <2025-06-23 周一>
303. Range Sum Query - Immutable <2025-05-21 周三>

5. Math

5.1. Modulo

Question Time
2845. Count of Interesting Subarrays <2025-05-20 周二>
   

5.2. Digits

Question Time
556. Next Greater Element III <2025-05-21 周三>
7. Reverse Integer <2025-05-21 周三>

5.3. Permutation

Question Time
31. Next Permutation <2025-05-21 周三>
556. Next Greater Element III <2025-05-21 周三>
1920. Build Array from Permutation <2025-05-24 周六>
   

6. Offline

Question Time
2940. Find Building Where Alice and Bob Can Meet <2025-05-25 周日>

7. Binary Search

Question Time
2071. Maximum Number of Tasks You Can Assign <2025-05-25 周日>

8. Monotonic Stack

Question Time
496. Next Greater Element I <2025-06-07 周六>
42. Trapping Rain Water <2025-06-07 周六>
503. Next Greater Element II <2025-06-07 周六>
907. Sum of Subarray Minimums <2025-06-07 周六>

9. TODO Backtracking

10. Simulation

Question Time
838. Push Dominoes <2025-06-07 周六>

11. Tricks

Question Time Discussion
1007. Minimum Domino Rotations For Equal Row <2025-05-03 周六> link
     

12. TODO Graph

12.1. DFS

12.2. TODO shortest path

12.3. Connected Components

Question Time
3532. Path Existence Queries in a Graph I <2025-05-25 周日>
200. Number of Islands <2025-04-30 周三>

12.4. TODO Topological Sort

12.5. TODO Tree

12.6. Cycle

Question Time
1920. Build Array from Permutation <2025-05-06 周二>
3551. Minimum Swaps to Sort by Digit Sum <2025-05-17 周六>
   

13. Dynamic Programming

Question Time Topics Covered
3578. Count Partitions With Max-Min Difference at Most K <2025-06-08 周日> DP, Mono Stack, Sliding Window, Modular

14. string

14.1. Trie

15. Computer Network

Question Time
Check if two ips are in the same subnet <2025-07-12 周六>

16. Company Tag

16.1. Google

Question Time  
2. Add Two Numbers <2025-06-13 周五>  
9. Palindrome Number <2025-06-13 周五> Corner cases
121. Best Time to Buy and Sell Stock <2025-06-13 周五>  
122. Best Time to Buy and Sell Stock II <2025-06-14 周六> State Machine + DP
3574. Maximize Subarray GCD Score <2025-06-15 周日>