dsa1 min read
01 Matrix — Distance to Nearest 0 (Multi-Source BFS)
For each cell find distance to nearest 0. Multi-source BFS from all 0s simultaneously gives optimal O(m*n) solution.
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Shortest-path
10 articles
dsa1 min read
Shortest Path in Binary Matrix — BFS 8-Directional
Find shortest clear path from top-left to bottom-right in binary matrix using 8-directional BFS. Return path length or -1.
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dsa1 min read
Nearest Exit from Entrance in Maze — BFS
BFS from entrance in a maze to find nearest exit (border empty cell). Classic BFS shortest path with exit condition.
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Snakes and Ladders — BFS on Board State
Minimum dice rolls to reach square n^2. Convert board position to 2D coordinates (Boustrophedon order), BFS on board states.
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dsa1 min read
Network Delay Time — Dijkstra Shortest Paths
Find time for signal to reach all nodes. Single-source shortest path (Dijkstra) from node k; answer is max of all shortest distances.
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dsa1 min read
Cheapest Flights Within K Stops — Bellman-Ford / BFS
Find cheapest flight from src to dst with at most k stops. Bellman-Ford with k+1 iterations or BFS level-by-level.
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dsa2 min read
Floyd-Warshall — All-Pairs Shortest Path
Compute shortest paths between all pairs of vertices using Floyd-Warshall's O(V³) DP. Handles negative weights and detects negative cycles.
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dsa2 min read
Bellman-Ford — SSSP with Negative Edges and Cycle Detection
Compute single-source shortest paths in graphs with negative weight edges using Bellman-Ford. V-1 relaxation passes detect negative cycles on the Vth pass.
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dsa2 min read
Dijkstra Advanced — Modified Dijkstra Patterns (K Stops, States, Constraints)
Advanced Dijkstra patterns: state-space Dijkstra for problems with extra constraints like K stops, fuel limit, or restricted nodes. The key is augmenting the state beyond just the node.
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dsa2 min read
Number of Ways to Arrive at Destination — Dijkstra + Count
Count the number of shortest paths from source to destination using modified Dijkstra that tracks both minimum distance and path count simultaneously.
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