56 lines
1.5 KiB
JavaScript
56 lines
1.5 KiB
JavaScript
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const Queue = require('./queue');
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const Graph = require('./graph');
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function findPathWithDijkstra(cities, roads, startNode, endNode) {
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const graph = new Graph();
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// Add cities and roads to graph
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for (let city of cities) {
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graph.addNode(city.id)
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}
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for (let { start_city_id, end_city_id, distance } of roads) {
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graph.addEdge(start_city_id, end_city_id, distance)
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}
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// Dijkstra path search algo
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let times = {};
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let backtrace = {};
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let queue = new Queue();
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times[startNode] = 0;
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graph.nodes.forEach(node => {
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if (node !== startNode) {
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times[node] = Infinity
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}
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});
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queue.enqueue([startNode, 0]);
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while (queue.size()) {
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let shortestStep = queue.dequeue();
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let currentNode = shortestStep[0];
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graph.adjacencyList[currentNode].forEach(neighbor => {
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let time = times[currentNode] + neighbor.distance;
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if (time < times[neighbor.node]) {
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times[neighbor.node] = time;
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backtrace[neighbor.node] = currentNode;
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queue.enqueue([neighbor.node, time]);
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}
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});
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}
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let path = [endNode];
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let lastStep = endNode; while(lastStep !== startNode) {
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path.unshift(backtrace[lastStep])
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lastStep = backtrace[lastStep]
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}
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// return `Path is ${path} and time is ${times[endNode]}`
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return {path, distance: times[endNode]}
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}
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module.exports = findPathWithDijkstra;
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