lgrthms/lib/algorithms/graphs/topologicalSort.js

Algorithms and data structures for your JavaScript and TypeScript projects 🧑‍💻

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.topologicalSort = void 0;
const Graph_1 = require("../../dataStructures/Graph");
function topologicalSort(array, dependencies, get) {
    get = get ? get : (element) => element;
    const graph = buildGraph(array, dependencies, get);
    const sorted = [];
    for (const element of array) {
        const nodeId = get(element);
        depthFirstTraverseAndPopulateSortedArray(nodeId, graph, sorted);
    }
    return sorted;
}
exports.topologicalSort = topologicalSort;
function buildGraph(array, dependencies, get) {
    const graph = new Graph_1.Graph();
    for (const element of array) {
        const id = get(element);
        const info = { visited: false, visiting: false };
        graph.addNode({ element, info }, id);
    }
    for (const { dependency, prerequisite } of dependencies) {
        graph.addEdge(dependency, prerequisite);
    }
    return graph;
}
function depthFirstTraverseAndPopulateSortedArray(nodeId, graph, sorted) {
    const node = graph.getNode(nodeId);
    if (node.value.info.visited) {
        return;
    }
    if (node.value.info.visiting) {
        throw new Error(`Invalid dependencies array, detected cycle at node ${nodeId}`);
    }
    node.value.info.visiting = true;
    for (const neighborId in node.edges) {
        depthFirstTraverseAndPopulateSortedArray(neighborId, graph, sorted);
    }
    node.value.info.visiting = false;
    node.value.info.visited = true;
    sorted.push(node.value.element);
}