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DijkstraSmallestPath

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after fixing some errors.
This commit is contained in:
Nur69
2020-04-19 17:01:26 +02:00
committed by GitHub
parent cdab9f9a3c
commit 1b3b125723
1 changed files with 35 additions and 19 deletions
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50
maths/DijkstraSmallestPath.js
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@ -1,11 +1,12 @@
// starting at s
function solve(graph, s) { function solve(graph, s) {
var solution = {}; var solutions = {};
solutions[s] = []; solutions[s] = [];
solutions[s].dist = 0; solutions[s].dist = 0;
while(true) { while(true) {
var parent = null; var p = null;
var nearest = null; var neighbor = null;
var dist = Infinity; var dist = Infinity;
@ -14,39 +15,38 @@ function solve(graph, s) {
continue continue
var ndist = solutions[n].dist; var ndist = solutions[n].dist;
var adj = graph[n]; var adj = graph[n];
//for each of its adjacent nodes...
for(var a in adj) { for(var a in adj) {
//without a solution already...
if(solutions[a]) if(solutions[a])
continue; continue;
//choose nearest node with lowest *total* cost
var d = adj[a] + ndist; var d = adj[a] + ndist;
if(d < dist) { if(d < dist) {
//reference parent
parent = solutions[n]; p = solutions[n];
nearest = a; neighbor = a;
dist = d; dist = d;
} }
} }
} }
//no more solutions
if(dist === Infinity) { if(dist === Infinity) {
break; break;
} }
solutions[nearest] = parent.concat(nearest); //extend parent's solution path
solutions[neighbor] = p.concat(neighbor);
solutions[nearest].dist = dist; //extend parent's cost
solutions[neighbor].dist = dist;
} }
return solutions; return solutions;
} }
//create graph
var graph = {}; var graph = {};
\\create graph
var layout = { var layout = {
'R': ['2'], 'R': ['2'],
'2': ['3','4'], '2': ['3','4'],
@ -66,7 +66,6 @@ var layout = {
} }
//convert uni-directional to bi-directional graph //convert uni-directional to bi-directional graph
// needs to look like: where: { a: { b: cost of a->b }
// var graph = { // var graph = {
// a: {e:1, b:1, g:3}, // a: {e:1, b:1, g:3},
// b: {a:1, c:1}, // b: {a:1, c:1},
@ -100,3 +99,20 @@ for(var s in solutions) {
if(!solutions[s]) continue; if(!solutions[s]) continue;
console.log(" -> " + s + ": [" + solutions[s].join(", ") + "] (dist:" + solutions[s].dist + ")"); console.log(" -> " + s + ": [" + solutions[s].join(", ") + "] (dist:" + solutions[s].dist + ")");
} }
// From '10' to
// -> 2: [7, 5, 4, 2] (dist:4)
// -> 3: [7, 5, 4, 3] (dist:4)
// -> 4: [7, 5, 4] (dist:3)
// -> 5: [7, 5] (dist:2)
// -> 6: [7, 5, 4, 3, 6] (dist:5)
// -> 7: [7] (dist:1)
// -> 8: [7, 5, 4, 8] (dist:4)
// -> 9: [7, 5, 4, 3, 13, 14, 9] (dist:7)
// -> 10: [] (dist:0)
// -> 11: [7, 5, 11] (dist:3)
// -> 12: [7, 5, 11, 12] (dist:4)
// -> 13: [7, 5, 4, 3, 13] (dist:5)
// -> 14: [7, 5, 4, 3, 13, 14] (dist:6)
// -> 15: [7, 5, 4, 3, 6, 15] (dist:6)
// -> R: [7, 5, 4, 2, R] (dist:5)