A Collection of Code Snippets in as Many Programming Languages as Possible

This project is maintained by TheRenegadeCoder

Welcome to the Dijkstra in Mathematica page! Here, you'll find the source code for this program as well as a description of how the program works.

```
(* Code *)
(* This is easy to do using Mathematica graph operations: *)
dijkstra = Function[{am, from, to},
(* sum the edge weights *)
Total @ Module[
{g = WeightedAdjacencyGraph[am /. 0 -> \[Infinity] (* needed to indicate no edge *)]},
PropertyValue[{ (* find the edge weights *)
g,
(* convert the list of path vertices into a list of edges *)
Apply[UndirectedEdge] /@ Partition[
(* find shortest path (cheating!) *)
FindShortestPath[g, from, to, Method -> "Dijkstra"],
2, 1]},
EdgeWeight]]];
(* The outer function provides the 'user interface': *)
dijkstraMain = Function[{values, from, to},
Module[{e = "Usage: please provide three inputs: a serialized matrix, a source node and a destination node"},
Catch[
Apply[
Function[{v, f, t},
Module[{l = Sqrt[Length[v]], w},
w = dijkstra[
Partition[v,(* convert to square matrix *)
(* compute square dimension *)
If[IntegerQ[l], l, Throw[e]]],
If[f < l, 1 + f, Throw[e]],(* Mathematica indices are 1-based *)
If[t < l, 1 + t, Throw[e]]];
(* Specifically detect the case where no path was found;
note that FindShortestPath just returns zero in this case,
which it would also do if the source and destination vertices are the same. *)
If[w == 0 \[And] f != t, Throw[e], w]]]]@
Map[
(* convert string to integer, or throw *)
s \[Function] If[StringMatchQ[s, DigitCharacter ..],
FromDigits[s],
Throw[e]],
(* construct arguments: list of weights, source node, destination node *)
{
StringSplit[If[StringLength[values] > 0, values, Throw[e]], ", "],
from, to
},
{-1} (* at each leaf *)]]]];
(* Valid Tests *)
Print /@ Apply[dijkstraMain] /@ {
{"0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "0", "1"}
};
(* Invalid Tests *)
dijkstraMain["1, 0, 3, 0, 5, 1", "1", "2"]
dijkstraMain["0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "0", ""]
dijkstraMain["0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "", ""]
dijkstraMain["0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "-1", "2"]
dijkstraMain["0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "1", "-2"]
dijkstraMain["0, 2, 0, -6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, -6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "1", "2"]
dijkstraMain["0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0", "1", "10"]
dijkstraMain["0, 0, 0, 0", "0", "1"]
```

Dijkstra in Mathematica was written by:

- Ben Hekster

If you see anything you'd like to change or update, please consider contributing.

No 'How to Implement the Solution' section available. Please consider contributing.

No 'How to Run the Solution' section available. Please consider contributing.