DSA 75 Sprint
75 curated questions across 16 patterns. Master the core topics FAANG interviewers ask most.
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Day Streak
Day 1 Objectives
0 of 2 problems completedAll 75 DSA 75 problems
The complete list, grouped by the pattern each problem is meant to teach and ordered the way the sprint works through them. Start at the top and move down — the ordering is the curriculum, not an arbitrary sort.
Every problem links to its pattern lesson, where the technique is explained and paired with an interactive visualizer you step through yourself. Problems marked Free open without payment. Progress tracking, streaks and the day-by-day study plan need an account.
Two Pointers · 6 problems
Attack the problem from two angles. Optimize O(n²) to O(n).
- Two Sum II - Sorted ArrayFreeMedium
- 3SumMedium
- Move ZeroesEasy
- Sort ColorsMedium
Sliding Window · 5 problems
Efficiently process contiguous subarrays and substrings.
- Maximum Sum Subarray of Size KFreeEasy
Stack · 7 problems
LIFO mastery — parentheses, monotonic stacks, and expression parsing.
- Valid ParenthesesFreeEasy
- Min StackMedium
- Daily TemperaturesMedium
- Decode StringMedium
Binary Search · 3 problems
Divide and conquer to achieve O(log n) search efficiency.
- Binary SearchFreeEasy
- Koko Eating BananasMedium
Intervals · 6 problems
Merge, insert, and process overlapping time ranges.
- Merge IntervalsFreeMedium
- Insert IntervalMedium
- Meeting RoomsEasy
- Meeting Rooms IIMedium
Linked List · 5 problems
Pointer manipulation, cycle detection, and list reversal.
- Linked List CycleFreeEasy
- Remove Nth Node From EndMedium
- Reorder ListMedium
- Swap Nodes in PairsMedium
Heap / Priority Queue · 4 problems
Efficient min/max element access for streaming and top-K problems.
- Kth Largest Element in a StreamFreeEasy
- Find K Closest ElementsMedium
DFS — Trees · 6 problems
Recursion on tree structures: depth, paths, and validation.
- Maximum Depth of Binary TreeFreeEasy
- Path SumEasy
- Path Sum IIMedium
BFS — Level Order · 5 problems
Layer-by-layer traversal for shortest paths and level processing.
- Binary Tree Right Side ViewFreeMedium
- Rotting OrangesMedium
- 01 MatrixMedium
- Bus RoutesHard
Graphs · 7 problems
Connectivity, topological sort, and cycle detection.
- Number of IslandsFreeMedium
- Clone GraphMedium
- Course ScheduleMedium
- Course Schedule IIMedium
- Surrounded RegionsMedium
- Graph Valid TreeMedium
Backtracking · 4 problems
Explore all possibilities and prune invalid paths.
- SubsetsFreeMedium
- Combination SumMedium
- Generate ParenthesesMedium
- Word SearchMedium
Dynamic Programming · 7 problems
Optimal substructure meets overlapping subproblems.
- Longest Increasing SubsequenceFreeMedium
- Unique PathsMedium
- Decode WaysMedium
- Word BreakMedium
- Maximal SquareMedium
- Counting BitsEasy
Greedy · 3 problems
Locally optimal choices that lead to globally optimal solutions.
- Best Time to Buy and Sell StockFreeEasy
- Jump GameMedium
- Gas StationMedium
Trie · 2 problems
Prefix tree for efficient string search and autocomplete.
- Implement Trie (Prefix Tree)FreeMedium
Prefix Sum · 2 problems
Precompute once, then answer any range query in constant time.
- Subarray Sum Equals KFreeMedium
- Count Vowels in RangesMedium
Matrices · 3 problems
In-place manipulation, spiral traversal, and grid transformations.
- Spiral MatrixFreeMedium
- Rotate ImageMedium
- Set Matrix ZeroesMedium