Depth and breadth-first traversal algorithm for Java implementation graphs

Overview:

Recently to learn to write web crawler. So the depth and breadth of the map to search all over again.

Figure structure Show:

implementation process:first, let's look at the implementation of the graph structure in the code. There are three blocks of logic:
1. The nodes in the diagram:

public class Graphnode {public list<graphedge> edgelist = null;private string label = "";p ublic graphnode (String lab EL) {This.label = label;if (edgelist = = null) {edgelist = new arraylist<graphedge> ();}} /** * Add an edge to the current node * Graphnode * @param edge * Join the Edge */public void Addedgelist (Graphedge edge) {Edgelist.add (edge);} Public String Getlabel () {return label;}}

2. Edges in the diagram:

public class Graphedge {private Graphnode nodeleft;private graphnode noderight;/** * @param nodeleft * left side of Edge * @param noder Ight * Side right end */public Graphedge (Graphnode nodeleft, Graphnode noderight) {this.nodeleft = Nodeleft;this.noderight = NodeRig HT;} Public Graphnode Getnodeleft () {return nodeleft;} Public Graphnode Getnoderight () {return noderight;}}

3. Combine nodes and edges into one graph structure:

public class Mygraph {private list<graphnode> nodes = Null;public void initgraph (int n) {if (nodes = = null) {nodes = New arraylist<graphnode> ();} Graphnode node = null;for (int i = 0; i < n; i++) {node = new Graphnode (string.valueof (i)); Nodes.Add (node);}} public void initgraph (int n, Boolean b) {initgraph (n); Graphedge edge01 = new Graphedge (nodes.get (0), Nodes.get (1)); Graphedge edge02 = new Graphedge (nodes.get (0), Nodes.get (2)); Graphedge edge13 = new Graphedge (Nodes.get (1), Nodes.get (3)); Graphedge edge14 = new Graphedge (Nodes.get (1), Nodes.get (4)); Graphedge edge25 = new Graphedge (Nodes.get (2), Nodes.get (5)); Graphedge edge26 = new Graphedge (Nodes.get (2), Nodes.get (6)); Graphedge edge37 = new Graphedge (Nodes.get (3), Nodes.get (7)); Graphedge edge47 = new Graphedge (Nodes.get (4), Nodes.get (7)); Graphedge edge56 = new Graphedge (Nodes.get (5), Nodes.get (6)), Nodes.get (0). Addedgelist (EDGE01); nodes.get (0). Addedgelist (EDGE02); Nodes.get (1). Addedgelist (EDGE13); Nodes.get (1). Addedgelist (EdgeNodes.get (2). Addedgelist (Edge25); Nodes.get (2). Addedgelist (Edge26); Nodes.get (3). Addedgelist (EDGE37); Nodes.get (4). Addedgelist (edge47); Nodes.get (5). Addedgelist (edge56);} public void Initgraph () {Initgraph (8, false);} Public list<graphnode> Getgraphnodes () {return nodes;}}

With the structure of the graph, we are able to do some practical work.
Depth-First search:

public class Dfsearch {/** * Depth traversal * Dfsearch * @param node * Current node * @param visited * interviewed node list */public void Searchtravers ing (graphnode node, list<graphnode> visited) {//infer whether to traverse the if (Visited.contains (node)) {return;} Visited.add (node); System.out.println ("node:" + Node.getlabel ()); for (int i = 0; i < node.edgeList.size (); i++) {searchtraversing (Node.edge List.get (i). Getnoderight (), visited);}}

Breadth-First search:

public class Bfsearch {/** * Breadth First search * Bfsearch * @param node * Search for portal nodes */public void searchtraversing (Graphnode node) {Lis T<graphnode> visited = new arraylist<graphnode> (); The elements that have been interviewed queue<graphnode> q = new linkedlist<graphnode> (); Use the queue to hold the element Q.offer (node) to traverse sequentially, while (!q.isempty ()) {Graphnode Currnode = Q.poll (); if (!visited.contains (Currnode)) { Visited.add (Currnode); System.out.println ("node:" + Currnode.getlabel ()); for (int i = 0; i < currNode.edgeList.size (); i++) {Q.offer (currnode.e Dgelist.get (i). Getnoderight ());}}}}

Execution Result:

source code Download:

http://download.csdn.net/detail/u013761665/8968443

Depth and breadth-first traversal algorithm for Java implementation graphs