Primary = company-Google-thirtydays.csv (rolling ~June 2025 LeetCode 30-day tag snapshot, 183 rows) sorted by Frequency descending; take the 52 highest-frequency non-Database problems (cutoff at the 46.6 frequency tier), swapping the trivial 'Add Two Integers' pickup for the phone-screen staple Valid Parentheses = 53; then keep all 20 hxu296-google-2022 top-occurrence classics, 3 of which (Two Sum, Number of Islands, Subarray Sum Equals K) are already in the base and the other 17 appended as slow-burn classics a 30-day window structurally drops = 70 total (the cap).
Arrays & Hashing
- Two SumEasy
- Longest Consecutive SequenceMedium
- Valid AnagramEasy
- Group AnagramsMedium
- Contains DuplicateEasy
- Majority ElementEasy
- Maximum Product of Three NumbersEasy
- Rotate ArrayMedium
Two Pointers
Sliding Window
Stack
Binary Search
Linked List
- Add Two NumbersMedium
- Reverse Linked ListEasy
- LRU CacheMedium
Trees
Backtracking
Graphs
- Number of IslandsMedium
1-D DP
- House RobberMedium
2-D DP
- Unique PathsMedium
- Predict the WinnerMedium
Intervals
- Merge IntervalsMedium
- Meeting Rooms IIMedium
Math & Geometry
- Plus OneEasy
- Happy NumberEasy
- Palindrome NumberEasy
Strings
Bit Manipulation
- Reverse IntegerMedium