Very unfamilar with the problems, need to practice a lot.
| Problem | Difficulty | Comments |
| -------------------------------------------------------------------------------------------------------------------------------------- | ------------- | --------------------------------------------------------- | --- | ------- |
| 611. Valid Triangle Number | Medium | How to iterate the 3 pointers and update count correctly? |
| 1539. Kth Missing Positive Number | Easy | arr[i] - i is the count of missing numbers. |
| 705. Design HashSet | Easy | The whole implementation for each approach. |
| 1750. Minimum Length of String After Deleting Similar Ends | Medium (1501) | How not to intersect? |
| 923. 3Sum With Multiplicity | Medium (1710) | Implementation details. |
| 844. Backspace String Compare | Easy (1227) | while (s < n | | t < n) |
| 2337. Move Pieces to Obtain a String | Medium (1693) | while (s < n | | t < n) |
Somewhat familiar with the problems, need to practice some times.
| Problem | Difficulty | Comments |
|---|---|---|
| 826. Most Profit Assigning Work | Medium (1708) | How to find the max profit among the tasks from 0..j difficulty? |
| 1351. Count Negative Numbers in a Sorted Matrix | Easy | How to iterate to count(≤ x)? |
| 729. My Calendar I | Medium | Implementation details. |
| 1146. Snapshot Array | Medium (1770) | Key intuitions |
| 633. Sum of Square Numbers | Medium | Implementation detail: Iteration range, how to check? |
| 948. Bag of Tokens | Medium (1762) | Implementation details. |
| 922. Sort Array By Parity II | Easy (1173) | In-place |
| 925. Long Pressed Name | Easy | Key intuition and how two pointers work. |
| 380. Insert Delete GetRandom O(1) | Medium | I made a critical mistake in the remove(). |
| 381. Insert Delete GetRandom O(1) - Duplicates allowed | Hard | Again, remove() is critical. |
Famililar with the problems, just need to check if I can solve them quickly.
| Problem | Difficulty | Comments |
|---|---|---|
| 2779. Maximum Beauty of an Array After Applying Operation | Medium | nums[i] +- k pattern. |
| 410. Split Array Largest Sum | Hard | How to interpret the problem? |
| 1679. Max Number of K-Sum Pairs | Medium (1345) | Multiple two sum == k. |
219. Contains Duplicate II 624. Maximum Distance in Arrays
Not familiar with the problems or made mistakes before, but it's solved now.