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loianeloiane
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added chapter 09
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‎chapter08.zip

-2.54 KB
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‎chapter09/01-Graph.js

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function Graph() {
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var vertices = []; //list
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var adjList = new Dictionary();
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this.addVertex = function(v){
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vertices.push(v);
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adjList.set(v, []); //initialize adjacency list with array as well;
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};
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this.addEdge = function(v, w){
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adjList.get(v).push(w);
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//adjList.get(w).push(v); //commented to run the improved DFS with topological sorting
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};
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this.toString = function(){
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var s = '';
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for (var i=0; i<vertices.length; i++){
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s += vertices[i] + ' -> ';
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var neighbors = adjList.get(vertices[i]);
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for (var j=0; j<neighbors.length; j++){
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s += neighbors[j] + ' ';
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}
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s += '\n';
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}
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return s;
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};
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var initializeColor = function(){
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var color = [];
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for (var i=0; i<vertices.length; i++){
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color[vertices[i]] = 'white';
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}
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return color;
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};
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this.bfs = function(v, callback){
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var color = initializeColor(),
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queue = new Queue();
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queue.enqueue(v);
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while (!queue.isEmpty()){
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var u = queue.dequeue(),
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neighbors = adjList.get(u);
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color[u] = 'grey';
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for (var i=0; i<neighbors.length; i++){
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var w = neighbors[i];
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if (color[w] === 'white'){
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color[w] = 'grey';
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queue.enqueue(w);
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}
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}
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color[u] = 'black';
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if (callback) {
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callback(u);
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}
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}
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};
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this.dfs = function(callback){
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var color = initializeColor();
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for (var i=0; i<vertices.length; i++){
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if (color[vertices[i]] === 'white'){
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dfsVisit(vertices[i], color, callback);
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}
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}
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};
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var dfsVisit = function(u, color, callback){
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color[u] = 'grey';
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if (callback) {
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callback(u);
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}
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console.log('Discovered ' + u);
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var neighbors = adjList.get(u);
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for (var i=0; i<neighbors.length; i++){
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var w = neighbors[i];
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if (color[w] === 'white'){
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dfsVisit(w, color, callback);
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}
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}
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color[u] = 'black';
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console.log('explored ' + u);
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};
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this.BFS = function(v){
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var color = initializeColor(),
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queue = new Queue(),
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d = [],
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pred = [];
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queue.enqueue(v);
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for (var i=0; i<vertices.length; i++){
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d[vertices[i]] = 0;
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pred[vertices[i]] = null;
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}
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while (!queue.isEmpty()){
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var u = queue.dequeue(),
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neighbors = adjList.get(u);
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color[u] = 'grey';
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for (i=0; i<neighbors.length; i++){
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var w = neighbors[i];
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if (color[w] === 'white'){
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color[w] = 'grey';
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d[w] = d[u] + 1;
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pred[w] = u;
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queue.enqueue(w);
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}
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}
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color[u] = 'black';
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}
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return {
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distances: d,
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predecessors: pred
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};
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};
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var time = 0;
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this.DFS = function(){
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var color = initializeColor(),
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d = [],
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f = [],
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p = [];
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time = 0;
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for (var i=0; i<vertices.length; i++){
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f[vertices[i]] = 0;
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d[vertices[i]] = 0;
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p[vertices[i]] = null;
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}
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for (i=0; i<vertices.length; i++){
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if (color[vertices[i]] === 'white'){
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DFSVisit(vertices[i], color, d, f, p);
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}
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}
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return {
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discovery: d,
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finished: f,
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predecessors: p
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};
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};
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var DFSVisit = function(u, color, d, f, p){
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console.log('discovered ' + u);
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color[u] = 'grey';
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d[u] = ++time;
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var neighbors = adjList.get(u);
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for (var i=0; i<neighbors.length; i++){
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var w = neighbors[i];
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if (color[w] === 'white'){
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p[w] = u;
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DFSVisit(w,color, d, f, p);
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}
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}
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color[u] = 'black';
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f[u] = ++time;
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console.log('explored ' + u);
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};
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}

‎chapter09/02-UsingGraphs.html

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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="UTF-8">
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<title></title>
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</head>
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<body>
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<script type="text/javascript" src="01-Graph.js"></script>
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<script type="text/javascript" src="../chapter04/01-Queue.js"></script>
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<script type="text/javascript" src="../chapter03/01-Stack.js"></script>
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<script type="text/javascript" src="../chapter07/01-Dictionaries.js"></script>
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<script type="text/javascript" src="02-UsingGraphs.js"></script>
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</body>
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</html>

‎chapter09/02-UsingGraphs.js

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var graph = new Graph();
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var myVertices = ['A','B','C','D','E','F','G','H','I'];
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for (var i=0; i<myVertices.length; i++){
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graph.addVertex(myVertices[i]);
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}
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graph.addEdge('A', 'B');
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graph.addEdge('A', 'C');
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graph.addEdge('A', 'D');
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graph.addEdge('C', 'D');
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graph.addEdge('C', 'G');
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graph.addEdge('D', 'G');
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graph.addEdge('D', 'H');
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graph.addEdge('B', 'E');
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graph.addEdge('B', 'F');
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graph.addEdge('E', 'I');
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console.log('********* printing graph ***********');
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console.log(graph.toString());
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console.log('********* bfs ***********');
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function printNode(value){
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console.log('Visited vertex: ' + value);
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}
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graph.bfs(myVertices[0], printNode);
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console.log('********* dfs ***********');
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graph.dfs();
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console.log('********* sorthest path - BFS ***********');
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var shortestPathA = graph.BFS(myVertices[0]);
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console.log(shortestPathA.distances);
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console.log(shortestPathA.predecessors);
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//from A to all other vertices
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var fromVertex = myVertices[0];
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for (i=1; i<myVertices.length; i++){
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var toVertex = myVertices[i],
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path = new Stack();
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for (var v=toVertex; v!== fromVertex; v=shortestPathA.predecessors[v]) {
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path.push(v);
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}
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path.push(fromVertex);
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var s = path.pop();
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while (!path.isEmpty()){
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s += ' - ' + path.pop();
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}
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console.log(s);
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}
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console.log('********* topological sort - DFS ***********');
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//var result = graph.DFS();
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//console.log(result.discovery);
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//console.log(result.finished);
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//console.log(result.predecessors);
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graph = new Graph();
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myVertices = ['A','B','C','D','E','F'];
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for (i=0; i<myVertices.length; i++){
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graph.addVertex(myVertices[i]);
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}
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graph.addEdge('A', 'C');
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graph.addEdge('A', 'D');
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graph.addEdge('B', 'D');
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graph.addEdge('B', 'E');
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graph.addEdge('C', 'F');
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graph.addEdge('F', 'E');
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var result = graph.DFS();
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console.log(result.discovery);
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console.log(result.finished);
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console.log(result.predecessors);
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var fTimes = result.finished;
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s = '';
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for (var count=0; count<myVertices.length; count++){
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var max = 0;
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var maxName = null;
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for (i=0; i<myVertices.length; i++){
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if (fTimes[myVertices[i]] > max){
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max = fTimes[myVertices[i]];
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maxName = myVertices[i];
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}
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}
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s += ' - ' + maxName;
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delete fTimes[maxName];
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}
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console.log(s);

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