Dijkstra's Shortest Path
Interactive lab
Try it: Dijkstra's Shortest Path
How Dijkstra's algorithm finds shortest paths in a graph with non-negative edge weights by always finalising the closest unfinished node.
How it works
- Start with distance 0 at the source and ∞ everywhere else.
- Pick the unfinished node with the smallest distance; its distance is now final.
- Relax each edge: if going through this node is shorter, update the neighbour's distance and predecessor.
- Repeat; follow predecessors back from the target to read the path.
Default run (21 steps): Shortest paths from A. Every distance starts at ∞ except A = 0. … Shortest path A → H: A → B → C → F → H, total weight 11.
Simplified: Fixed 8-node undirected graph with integer weights 1–9. Draggable layout; weights and edges are editable.
Educational simulation
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