INDEX OF DRAWINGS
The why behind every DSA problem
Not solutions — reasoning. Every problem here is argued from brute force to optimal, with the one observation that unlocks it called out by name and animated step by step. The bar isn't "solved it once"; it's "could rebuild it from the observation."
79 problems drafted from Striver's A2Z sheet · 0 marked understood on this device
STEP 3 · ARRAYS
- ○Best Time to Buy and Sell StockEasy
- ○Two SumEasy
- ○Container With Most WaterMedium
- ○Sort an Array of 0s, 1s and 2sMedium
- ○Maximum Subarray Sum (Kadane's Algorithm)Medium
- ○Maximum Product SubarrayMedium
- ○Next PermutationMedium
- ○Spiral MatrixMedium
- ○Pascal's TriangleEasy
- ○Count Subarrays With Sum KMedium
- ○Count Subarrays With XOR KMedium
- ○3 SumMedium
STEP 4 · BINARY SEARCH
STEP 5 · STRINGS
STEP 7 · RECURSION
STEP 10 · SLIDING WINDOW
- ○Longest Substring Without Repeating CharactersMedium
- ○Max Consecutive Ones IIIMedium
- ○Longest Repeating Character ReplacementMedium
- ○Binary Subarrays With SumMedium
- ○Count Number of Nice SubarraysMedium
- ○Number of Substrings Containing All Three CharactersMedium
- ○Maximum Points You Can Obtain from CardsMedium
- ○Longest Substring with At Most K Distinct CharactersMedium
- ○Minimum Window SubstringHard
STEP 13 · BINARY TREES
- ○Maximum Depth of Binary TreeEasy
- ○Balanced Binary TreeEasy
- ○Diameter of Binary TreeEasy
- ○Binary Tree Maximum Path SumHard
- ○Same Tree (Check If Two Trees Are Identical)Easy
- ○Symmetric Binary TreeEasy
- ○Zigzag (Spiral) Level Order TraversalMedium
- ○Boundary Traversal of Binary TreeMedium
- ○Construct Binary Tree from Preorder and InorderMedium
- ○Morris Traversal (Inorder and Preorder)Medium
- ○All Nodes Distance K in Binary TreeMedium
STEP 14 · BINARY SEARCH TREES
- ○Insert Into a Binary Search TreeEasy
- ○Delete Node in a BSTMedium
- ○Validate Binary Search TreeMedium
- ○Lowest Common Ancestor of a BSTEasy
- ○Kth Smallest and Largest Element in a BSTMedium
- ○Two Sum in BST (Pair With Sum K)Medium
- ○Inorder Successor and Predecessor in BSTMedium
- ○Construct BST from Preorder TraversalMedium
- ○Recover BST (Two Nodes Swapped)Hard
- ○Largest BST Subtree in a Binary TreeHard
- ○Merge Two Binary Search TreesMedium
STEP 15 · GRAPHS
- ○Number of ProvincesMedium
- ○Number of IslandsMedium
- ○Flood FillEasy
- ○Rotting OrangesMedium
- ○Distance of Nearest Cell Having 1 (01 Matrix)Medium
- ○Surrounded RegionsMedium
- ○Number of EnclavesMedium
- ○Is Graph Bipartite?Medium
- ○Detect Cycle in an Undirected GraphMedium
- ○Detect Cycle in a Directed GraphMedium
- ○Word Ladder IIHard
- ○Number of Ways to Arrive at DestinationHard
- ○Swim in Rising WaterHard
- ○Most Stones Removed With Same Row or ColumnMedium
- ○Making A Large IslandHard
- ○Kosaraju's Algorithm (Strongly Connected Components)Hard
- ○Bridges in a Graph (Critical Connections)Hard