algorithm 49
- Tree - Shortest Bridge
- Tree - Count Sub Islands
- Tree - Longest Increasing Path in a Matrix
- Tree - Rotting Oranges
- Tree - Walls and Gates
- Tree - Surrounded Regions
- Tree - Swim in Rising Water
- Tree - Reorder Routes to Lead to City Zero
- Tree - Island Perimeter
- Tree - Pacific Atlantic Water Flow
- Tree - Number of Islands
- Tree - Course Schedule
- Tree - Course Schedule II
- Tree - Word Ladder
- Tree - Graph Valid Tree
- Tree - Clone Graph
- Tree - Network Delay Time
- Tree - Path Sum
- Tree - Trim a Binary Search Tree
- Tree - Flatten Binary Tree to Linked List
- Tree - Serialize and Deserialize Binary Tree
- Tree - Same Tree
- Tree - Construct Binary Tree from PreOrder and InOrder Traversal
- Tree - Binary Tree Maximum Path Sum
- Tree - Kth Smallest Element in a BST
- Tree - Diameter of a Binary Tree
- Tree - Sum Root to Leaf Numbers
- Tree - Binary Tree Right Side View
- Tree - Validate Binary Search Tree
- Linked List - Sort List
- Tree - Merge Two Binary Trees
- Tree - Count Good Nodes in Binary Tree
- Tree - Convert Sorted Array to Binary Search Tree
- Tree - Balanced Binary Tree
- Linked List - Swap Nodes in Pairs
- Linked List - Reverse Nodes in K-Group
- Linked List - Add Two Numbers
- Linked List - Reorder List
- Linked List - Remove Linked List Elements
- Sliding Window - Longest Repeating Character Replacement
- Sliding Window - Minimum Window Substring
- Binary Search - Search in Rotated Sorted Array II
- Sliding Window - Longest Substring Without Repeating Characters
- Sliding Window - Find Maximum in Sliding Window
- Binary Search - Search in Rotated Sorted Array
- Binary Search - Median of Two Sorted Arrays
- Binary Search - Find K Closest Elements
- Binary Search - Valid Perfect Square
- Two Pointers - Sort Colors