DSA 75 Sprint
75 curated questions across 16 patterns. Master the core topics FAANG interviewers ask most.
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 problemsAttack the problem from two angles. Optimize O(n²) to O(n).
- Two Sum II - Sorted ArrayFreeMedium
- 3SumMedium
- Move ZeroesEasy
- Sort ColorsMedium
Sliding Window
5 problemsEfficiently process contiguous subarrays and substrings.
- Maximum Sum Subarray of Size KFreeEasy
Stack
7 problemsLIFO mastery — parentheses, monotonic stacks, and expression parsing.
- Valid ParenthesesFreeEasy
- Min StackMedium
- Daily TemperaturesMedium
- Decode StringMedium
Binary Search
3 problemsDivide and conquer to achieve O(log n) search efficiency.
- Binary SearchFreeEasy
- Koko Eating BananasMedium
Intervals
6 problemsMerge, insert, and process overlapping time ranges.
- Merge IntervalsFreeMedium
- Insert IntervalMedium
- Meeting RoomsEasy
- Meeting Rooms IIMedium
Linked List
5 problemsPointer manipulation, cycle detection, and list reversal.
- Linked List CycleFreeEasy
- Remove Nth Node From EndMedium
- Reorder ListMedium
- Swap Nodes in PairsMedium
Heap / Priority Queue
4 problemsEfficient min/max element access for streaming and top-K problems.
- Kth Largest Element in a StreamFreeEasy
- Find K Closest ElementsMedium
DFS — Trees
6 problemsRecursion on tree structures: depth, paths, and validation.
- Maximum Depth of Binary TreeFreeEasy
- Path SumEasy
- Path Sum IIMedium
BFS — Level Order
5 problemsLayer-by-layer traversal for shortest paths and level processing.
- Binary Tree Right Side ViewFreeMedium
- Rotting OrangesMedium
- 01 MatrixMedium
- Bus RoutesHard
Graphs
7 problemsConnectivity, topological sort, and cycle detection.
- Number of IslandsFreeMedium
- Clone GraphMedium
- Course ScheduleMedium
- Course Schedule IIMedium
- Surrounded RegionsMedium
- Graph Valid TreeMedium
Backtracking
4 problemsExplore all possibilities and prune invalid paths.
- SubsetsFreeMedium
- Combination SumMedium
- Generate ParenthesesMedium
- Word SearchMedium
Dynamic Programming
7 problemsOptimal substructure meets overlapping subproblems.
- Longest Increasing SubsequenceFreeMedium
- Unique PathsMedium
- Decode WaysMedium
- Word BreakMedium
- Maximal SquareMedium
- Counting BitsEasy
Greedy
3 problemsLocally optimal choices that lead to globally optimal solutions.
- Best Time to Buy and Sell StockFreeEasy
- Jump GameMedium
- Gas StationMedium
Trie
2 problemsPrefix tree for efficient string search and autocomplete.
- Implement Trie (Prefix Tree)FreeMedium
Prefix Sum
2 problemsPrecompute once, then answer any range query in constant time.
- Subarray Sum Equals KFreeMedium
- Count Vowels in RangesMedium
Matrices
3 problemsIn-place manipulation, spiral traversal, and grid transformations.
- Spiral MatrixFreeMedium
- Rotate ImageMedium
- Set Matrix ZeroesMedium