lgrthms/lib/dataStructures/Graph.js

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

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Graph = void 0;
class Node {
    constructor(id, value) {
        this.id = id;
        this.value = value;
        this.edges = {};
    }
}
class Graph {
    constructor() {
        this.DEFAULT_WEIGHT = 1;
        this._nextId = 1;
        this._size = 0;
        this._graph = {};
    }
    get size() {
        return this._size;
    }
    // O(1) time | O(1) space
    getNode(id) {
        return this._graph[id];
    }
    // O(e) time | O(e) space — where e is the number of edges of the given node
    getEdges(id) {
        const node = this.getNode(id);
        if (!node) {
            return [];
        }
        return Object.keys(node.edges).map(neighborId => ({ neighborId, weight: node.edges[neighborId] }));
    }
    // O(1) time | O(1) space
    addNode(value, id) {
        if (id && !['number', 'string'].includes(typeof id)) {
            throw new Error('Cannot add node with given id, id must be a number or a string');
        }
        else if (typeof id === 'number') {
            this._nextId = id + 1;
        }
        else if (!id) {
            id = this._nextId;
            this._nextId++;
        }
        id = typeof id === 'number' ? String(id) : id;
        const node = new Node(id, value);
        this._graph[id] = node;
        this._size++;
        return node;
    }
    // O(1) time | O(1) space
    addEdge(nodeId, neighborId, weight = this.DEFAULT_WEIGHT) {
        if (!this._graph[nodeId]) {
            throw new Error('Cannot find node with given nodeId');
        }
        if (!this._graph[neighborId]) {
            throw new Error('Cannot find node with given neighborId');
        }
        const node = this._graph[nodeId];
        node.edges[neighborId] = weight;
    }
    // O(n) time | O(1) space
    removeNode(id) {
        if (!this._graph[id]) {
            return;
        }
        delete this._graph[id];
        for (const nodeId in this._graph) {
            this.removeEdge(nodeId, id);
        }
        this._size--;
    }
    // O(1) time | O(1) space
    removeEdge(nodeId, neighborId) {
        if (!this._graph[nodeId]) {
            return;
        }
        const node = this._graph[nodeId];
        delete node.edges[neighborId];
    }
    // O(1) time | O(1) space
    adjacent(nodeId, neighborId) {
        const node = this.getNode(nodeId);
        return Boolean(node && neighborId in node.edges);
    }
}
exports.Graph = Graph;