LeetCode 886: Possible Bipartition
A clear explanation of checking whether people can be split into two groups using graph coloring and bipartite graph detection.
Tag
Bfs
41 notes
LeetCode 623: Add One Row to Tree
A clear explanation of Add One Row to Tree using tree traversal and careful subtree reconnection.
LeetCode 864: Shortest Path to Get All Keys
A clear explanation of finding the minimum moves to collect all keys in a grid using BFS with key bitmasks.
LeetCode 863: All Nodes Distance K in Binary Tree
A clear explanation of finding all binary tree nodes at distance k from a target node by treating the tree as an undirected graph.
LeetCode 854: K-Similar Strings
A clear explanation of finding the minimum number of swaps needed to transform one anagram string into another using BFS.
LeetCode 818: Race Car
A dynamic programming solution for finding the shortest instruction sequence that drives a race car to the target position.
LeetCode 815: Bus Routes
A BFS solution for finding the minimum number of buses needed to travel from a source stop to a target stop.
LeetCode 785: Is Graph Bipartite?
A clear explanation of checking whether an undirected graph can be split into two independent sets using graph coloring.
LeetCode 773: Sliding Puzzle
A clear explanation of solving the 2 x 3 sliding puzzle using breadth-first search over board states.
LeetCode 752: Open the Lock
A clear explanation of solving Open the Lock using breadth-first search over lock states.
LeetCode 695: Max Area of Island
Find the largest connected island area in a binary grid using depth-first search.
LeetCode 690: Employee Importance
Compute the total importance of an employee and all direct and indirect subordinates using a hash map and depth-first search.
LeetCode 582: Kill Process
A clear graph traversal solution for finding all processes terminated when killing a target process.
LeetCode 515: Find Largest Value in Each Tree Row
A clear explanation of finding the maximum value at every depth of a binary tree using level-order traversal.
LeetCode 513: Find Bottom Left Tree Value
A clear explanation of finding the leftmost value in the deepest row of a binary tree using level-order traversal.
LeetCode 505: The Maze II
A clear explanation of finding the shortest rolling distance in a maze using Dijkstra’s algorithm.
LeetCode 490: The Maze
A clear explanation of deciding whether a rolling ball can stop at the destination using BFS or DFS over stopping cells.
LeetCode 444: Sequence Reconstruction
Check whether nums is the unique shortest supersequence of given subsequences using topological sorting.
LeetCode 433: Minimum Genetic Mutation
Find the minimum number of valid one-character gene mutations using breadth-first search.
LeetCode 429: N-ary Tree Level Order Traversal
Traverse an N-ary tree level by level using breadth-first search.
LeetCode 417: Pacific Atlantic Water Flow
A clear explanation of finding cells that can flow to both oceans using reverse graph traversal from the borders.
LeetCode 407: Trapping Rain Water II
A clear explanation of trapping rain water in a 2D elevation map using a min heap and boundary expansion.
LeetCode 364: Nested List Weight Sum II
A clear explanation of computing inverse depth weighted sum using level-order traversal.
LeetCode 323: Number of Connected Components in an Undirected Graph
A clear explanation of counting connected components using Union-Find and graph traversal.
LeetCode 317: Shortest Distance from All Buildings
A clear explanation of Shortest Distance from All Buildings using BFS from each building with distance and reach accumulation.
LeetCode 314: Binary Tree Vertical Order Traversal
A clear explanation of Binary Tree Vertical Order Traversal using BFS with column indices.
LeetCode 310: Minimum Height Trees
A clear explanation of Minimum Height Trees using leaf trimming to find the center of a tree.
LeetCode 301: Remove Invalid Parentheses
A clear explanation of Remove Invalid Parentheses using BFS to guarantee the minimum number of removals.
LeetCode 269: Alien Dictionary
A clear explanation of the Alien Dictionary problem using graph construction and topological sorting.
LeetCode 210: Course Schedule II
A clear explanation of finding a valid course ordering using topological sorting and cycle detection.
LeetCode 207: Course Schedule
A clear explanation of detecting cycles in a prerequisite graph using topological sorting and DFS.
LeetCode 133: Clone Graph
Create a deep copy of a connected undirected graph using DFS and a hash map from original nodes to cloned nodes.
LeetCode 130: Surrounded Regions
Capture surrounded O regions by marking border-connected O cells first, then flipping the remaining O cells.
LeetCode 127: Word Ladder
Use breadth-first search to find the shortest transformation sequence length between two words.
LeetCode 126: Word Ladder II
Find all shortest word transformation sequences using BFS to build shortest-path parents, then backtracking to reconstruct every answer.
LeetCode 117: Populating Next Right Pointers in Each Node II
A clear explanation of connecting next pointers in any binary tree using constant extra space.
LeetCode 116: Populating Next Right Pointers in Each Node
A clear explanation of connecting next pointers in a perfect binary tree using constant extra space.
LeetCode 111: Minimum Depth of Binary Tree
A clear explanation of finding the minimum depth of a binary tree using breadth-first search.
LeetCode 107: Binary Tree Level Order Traversal II
A clear explanation of returning binary tree levels from bottom to top using breadth-first search.
LeetCode 103: Binary Tree Zigzag Level Order Traversal
A clear explanation of zigzag level order traversal using breadth-first search and alternating level direction.
LeetCode 102: Binary Tree Level Order Traversal
A clear explanation of binary tree level order traversal using breadth-first search and a queue.