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197 lines (167 loc) 路 4.44 KB
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export default class Graph {
/**
* @param {boolean} isDirected
*/
constructor(isDirected = false) {
this.vertices = {};
this.edges = {};
this.isDirected = isDirected;
}
/**
* @param {GraphVertex} newVertex
* @returns {Graph}
*/
addVertex(newVertex) {
this.vertices[newVertex.getKey()] = newVertex;
return this;
}
/**
* @param {string} vertexKey
* @returns GraphVertex
*/
getVertexByKey(vertexKey) {
return this.vertices[vertexKey];
}
/**
* @param {GraphVertex} vertex
* @returns {GraphVertex[]}
*/
getNeighbors(vertex) {
return vertex.getNeighbors();
}
/**
* @return {GraphVertex[]}
*/
getAllVertices() {
return Object.values(this.vertices);
}
/**
* @return {GraphEdge[]}
*/
getAllEdges() {
return Object.values(this.edges);
}
/**
* @param {GraphEdge} edge
* @returns {Graph}
*/
addEdge(edge) {
// Try to find and end start vertices.
let startVertex = this.getVertexByKey(edge.startVertex.getKey());
let endVertex = this.getVertexByKey(edge.endVertex.getKey());
// Insert start vertex if it wasn't inserted.
if (!startVertex) {
this.addVertex(edge.startVertex);
startVertex = this.getVertexByKey(edge.startVertex.getKey());
}
// Insert end vertex if it wasn't inserted.
if (!endVertex) {
this.addVertex(edge.endVertex);
endVertex = this.getVertexByKey(edge.endVertex.getKey());
}
// Check if edge has been already added.
if (this.edges[edge.getKey()]) {
throw new Error('Edge has already been added before');
} else {
this.edges[edge.getKey()] = edge;
}
// Add edge to the vertices.
if (this.isDirected) {
// If graph IS directed then add the edge only to start vertex.
startVertex.addEdge(edge);
} else {
// If graph ISN'T directed then add the edge to both vertices.
startVertex.addEdge(edge);
endVertex.addEdge(edge);
}
return this;
}
/**
* @param {GraphEdge} edge
*/
deleteEdge(edge) {
// Delete edge from the list of edges.
if (this.edges[edge.getKey()]) {
delete this.edges[edge.getKey()];
} else {
throw new Error('Edge not found in graph');
}
// Try to find and end start vertices and delete edge from them.
const startVertex = this.getVertexByKey(edge.startVertex.getKey());
const endVertex = this.getVertexByKey(edge.endVertex.getKey());
startVertex.deleteEdge(edge);
endVertex.deleteEdge(edge);
}
/**
* @param {GraphVertex} startVertex
* @param {GraphVertex} endVertex
* @return {(GraphEdge|null)}
*/
findEdge(startVertex, endVertex) {
const vertex = this.getVertexByKey(startVertex.getKey());
if (!vertex) {
return null;
}
return vertex.findEdge(endVertex);
}
/**
* @return {number}
*/
getWeight() {
return this.getAllEdges().reduce((weight, graphEdge) => {
return weight + graphEdge.weight;
}, 0);
}
/**
* Reverse all the edges in directed graph.
* @return {Graph}
*/
reverse() {
/** @param {GraphEdge} edge */
this.getAllEdges().forEach((edge) => {
// Delete straight edge from graph and from vertices.
this.deleteEdge(edge);
// Reverse the edge.
edge.reverse();
// Add reversed edge back to the graph and its vertices.
this.addEdge(edge);
});
return this;
}
/**
* @return {object}
*/
getVerticesIndices() {
const verticesIndices = {};
this.getAllVertices().forEach((vertex, index) => {
verticesIndices[vertex.getKey()] = index;
});
return verticesIndices;
}
/**
* @return {*[][]}
*/
getAdjacencyMatrix() {
const vertices = this.getAllVertices();
const verticesIndices = this.getVerticesIndices();
// Init matrix with infinities meaning that there is no ways of
// getting from one vertex to another yet.
const adjacencyMatrix = Array(vertices.length).fill(null).map(() => {
return Array(vertices.length).fill(Infinity);
});
// Fill the columns.
vertices.forEach((vertex, vertexIndex) => {
vertex.getNeighbors().forEach((neighbor) => {
const neighborIndex = verticesIndices[neighbor.getKey()];
adjacencyMatrix[vertexIndex][neighborIndex] = this.findEdge(vertex, neighbor).weight;
});
});
return adjacencyMatrix;
}
/**
* @return {string}
*/
toString() {
return Object.keys(this.vertices).toString();
}
}