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Array-based O(n^2) Dijkstra on a small directed weighted graph:
edges = [|
[(1, 4); (2, 1)]; (* 0 -> 1 (w=4), 2 (w=1) *)
[(3, 1)]; (* 1 -> 3 (w=1) *)
[(1, 2); (3, 5)]; (* 2 -> 1 (w=2), 3 (w=5) *)
[(4, 3)]; (* 3 -> 4 (w=3) *)
[] (* 4 sink *)
|]
Optimal path 0->2->1->3->4 has weight 1+2+1+3 = 7.
Tests: array-of-list-of-int-pair literal, List.iter with tuple
destructuring closure, in-place dist mutation, nested for + ref.
141 baseline programs total.
38 lines
672 B
OCaml
38 lines
672 B
OCaml
let n = 5
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let edges = [|
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[(1, 4); (2, 1)];
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[(3, 1)];
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[(1, 2); (3, 5)];
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[(4, 3)];
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[]
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|]
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let dijkstra src =
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let dist = Array.make n 1000000 in
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dist.(src) <- 0;
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let visited = Array.make n false in
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for _ = 0 to n - 1 do
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let u = ref (-1) in
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let best = ref 1000000 in
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for v = 0 to n - 1 do
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if (not visited.(v)) && dist.(v) < !best then begin
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best := dist.(v);
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u := v
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end
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done;
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if !u >= 0 then begin
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visited.(!u) <- true;
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List.iter (fun (v, w) ->
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if dist.(!u) + w < dist.(v) then
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dist.(v) <- dist.(!u) + w
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) edges.(!u)
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end
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done;
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dist
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;;
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let d = dijkstra 0 in
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d.(4)
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