73 lines
1.8 KiB
JavaScript
73 lines
1.8 KiB
JavaScript
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/* eslint-disable no-restricted-globals */
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import makeSolver from "../makeSolver";
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import { pathCost, distance } from "../cost";
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const nearestInsertion = async points => {
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// from the starting point
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const path = [points.shift()];
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//
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// INITIALIZATION - go to the nearest point first
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//
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points.sort((a, b) => distance(path[0], b) - distance(path[0], a));
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path.push(points.pop());
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self.setEvaluatingPaths(() => ({
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paths: [{ path }],
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cost: pathCost(path)
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}));
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await self.sleep();
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while (points.length > 0) {
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//
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// SELECTION - nearest point to the path
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//
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let [selectedDistance, selectedIdx] = [Infinity, null];
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for (const [freePointIdx, freePoint] of points.entries()) {
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for (const pathPoint of path) {
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const dist = distance(freePoint, pathPoint);
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if (dist < selectedDistance) {
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[selectedDistance, selectedIdx] = [dist, freePointIdx];
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}
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}
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}
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// get the next point to add
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const [nextPoint] = points.splice(selectedIdx, 1);
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//
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// INSERTION - find the insertion spot that minimizes distance
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//
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let [bestCost, bestIdx] = [Infinity, null];
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for (let i = 1; i < path.length; i++) {
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const insertionCost = pathCost([path[i - 1], nextPoint, path[i]]);
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if (insertionCost < bestCost) {
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[bestCost, bestIdx] = [insertionCost, i];
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}
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}
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path.splice(bestIdx, 0, nextPoint);
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self.setEvaluatingPaths(() => ({
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paths: [{ path }],
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cost: pathCost(path)
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}));
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await self.sleep();
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}
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// return to start after visiting all other points
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path.push(path[0]);
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const cost = pathCost(path);
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self.setEvaluatingPaths(() => ({
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paths: [{ path }],
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cost
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}));
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await self.sleep();
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self.setBestPath(path, cost);
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};
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makeSolver(nearestInsertion);
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