LeetCode 959: Regions Cut By Slashes
A clear explanation of counting regions formed by slashes using union find over four triangles per cell.
Tag
Graph
63 notes
LeetCode 847: Shortest Path Visiting All Nodes
A clear explanation of the Shortest Path Visiting All Nodes problem using multi-source BFS and bitmask state compression.
LeetCode 841: Keys and Rooms
A clear explanation of the Keys and Rooms problem using graph traversal from room 0.
LeetCode 839: Similar String Groups
A clear explanation of the Similar String Groups problem using graph connectivity and union-find.
LeetCode 834: Sum of Distances in Tree
A clear explanation of the Sum of Distances in Tree problem using tree DP, subtree sizes, and rerooting.
LeetCode 924: Minimize Malware Spread
A clear explanation of minimizing malware spread by analyzing connected components with Union Find.
LeetCode 913: Cat and Mouse
A clear explanation of Cat and Mouse using game states, reverse BFS, and topological propagation.
LeetCode 909: Snakes and Ladders
A clear explanation of Snakes and Ladders using breadth-first search over board squares.
LeetCode 886: Possible Bipartition
A clear explanation of checking whether people can be split into two groups using graph coloring and bipartite graph detection.
LeetCode 882: Reachable Nodes In Subdivided Graph
A clear explanation of counting reachable original and subdivided nodes using Dijkstra's shortest path algorithm.
LeetCode 997: Find the Town Judge
A clear explanation of identifying the town judge using trust indegree and outdegree counts.
LeetCode 996: Number of Squareful Arrays
A clear explanation of counting unique permutations where every adjacent pair sums to a perfect square using backtracking.
LeetCode 994: Rotting Oranges
A clear explanation of finding the minimum time for all oranges to rot using multi-source BFS.
LeetCode 990: Satisfiability of Equality Equations
A clear explanation of checking equality and inequality constraints using union-find.
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 851: Loud and Rich
A clear explanation of Loud and Rich using graph traversal, DFS, and memoization.
LeetCode 947: Most Stones Removed with Same Row or Column
A clear explanation of solving Most Stones Removed with Same Row or Column using connected components and union-find.
LeetCode 943: Find the Shortest Superstring
A clear explanation of solving Find the Shortest Superstring using pairwise overlaps and bitmask dynamic programming.
LeetCode 936: Stamping The Sequence
A clear explanation of solving Stamping The Sequence using reverse simulation and BFS-style processing.
LeetCode 935: Knight Dialer
A clear explanation of solving Knight Dialer using dynamic programming over the phone keypad graph.
LeetCode 934: Shortest Bridge
A clear explanation of solving Shortest Bridge using DFS to mark one island and BFS to expand toward the other island.
LeetCode 928: Minimize Malware Spread II
A clear explanation of solving Minimize Malware Spread II by removing each infected node and simulating the final malware spread.
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 802: Find Eventual Safe States
A graph traversal solution for finding all nodes that cannot reach a directed cycle.
LeetCode 797: All Paths From Source to Target
A clear explanation of finding every path from node 0 to node n - 1 in a directed acyclic graph using DFS and backtracking.
LeetCode 787: Cheapest Flights Within K Stops
A clear explanation of finding the cheapest flight route with at most k stops using bounded Bellman-Ford relaxation.
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 778: Swim in Rising Water
A clear explanation of finding the minimum time to reach the bottom-right cell using a priority queue and minimax path reasoning.
LeetCode 773: Sliding Puzzle
A clear explanation of solving the 2 x 3 sliding puzzle using breadth-first search over board states.
LeetCode 753: Cracking the Safe
A clear explanation of Cracking the Safe using a de Bruijn sequence and depth-first search over password states.
LeetCode 752: Open the Lock
A clear explanation of solving Open the Lock using breadth-first search over lock states.
LeetCode 721: Accounts Merge
A clear explanation of merging accounts that share emails using union find and sorted email groups.
LeetCode 743: Network Delay Time
Find the time needed for a signal to reach all nodes in a directed weighted graph using Dijkstra's algorithm.
LeetCode 742: Closest Leaf in a Binary Tree
Find the nearest leaf to a target node by converting the tree into an undirected graph and running breadth-first search.
LeetCode 737: Sentence Similarity II
Check sentence similarity with transitive word relationships using union-find.
LeetCode 685: Redundant Connection II
Find the directed edge to remove so a graph becomes a rooted tree again, handling both cycles and nodes with two parents.
LeetCode 684: Redundant Connection
Find the extra edge in an undirected graph that creates a cycle using Union-Find.
LeetCode 582: Kill Process
A clear graph traversal solution for finding all processes terminated when killing a target process.
LeetCode 568: Maximum Vacation Days
A clear explanation of Maximum Vacation Days using dynamic programming over weeks and cities.
LeetCode 547: Number of Provinces
A clear explanation of counting connected components in an undirected graph represented by an adjacency matrix.
LeetCode 505: The Maze II
A clear explanation of finding the shortest rolling distance in a maze using Dijkstra’s algorithm.
LeetCode 499: The Maze III
A clear explanation of finding the shortest rolling-ball path to the hole using Dijkstra with lexicographic tie-breaking.
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 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 399: Evaluate Division
A clear explanation of solving division equations using graph traversal and weighted edges.
LeetCode 332: Reconstruct Itinerary
A clear explanation of Reconstruct Itinerary using a directed graph and Hierholzer's algorithm.
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 310: Minimum Height Trees
A clear explanation of Minimum Height Trees using leaf trimming to find the center of a tree.
LeetCode 305: Number of Islands II
A clear explanation of Number of Islands II using Union-Find to dynamically merge connected land cells.
LeetCode 286: Walls and Gates
A multi-source BFS solution for filling each empty room with its shortest distance to the nearest gate.
LeetCode 277: Find the Celebrity
A two-pass solution for finding a celebrity using the knows API with O(n) calls and O(1) extra space.
LeetCode 269: Alien Dictionary
A clear explanation of the Alien Dictionary problem using graph construction and topological sorting.
LeetCode 261: Graph Valid Tree
A clear explanation of the Graph Valid Tree problem using Union Find to detect cycles and verify connectivity.
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 200: Number of Islands
A clear explanation of counting connected groups of land cells in a grid using DFS or BFS.
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 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.