Last active
April 26, 2016 02:39
-
-
Save appym/e392d64bdfa28e0dc16173f131dfb26c to your computer and use it in GitHub Desktop.
DFS and BFS
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// | |
public class Node | |
{ | |
public char label; | |
public boolean visited=false; | |
public Node(char l) | |
{ | |
this.label=l; | |
} | |
} | |
public class Graph | |
{ | |
public Node rootNode; | |
public ArrayList nodes=new ArrayList(); | |
public int[][] adjMatrix;//Edges will be represented as adjacency Matrix | |
int size; | |
public void setRootNode(Node n) | |
{ | |
this.rootNode=n; | |
} | |
public Node getRootNode() | |
{ | |
return this.rootNode; | |
} | |
public void addNode(Node n) | |
{ | |
nodes.add(n); | |
} | |
//This method will be called to make connect two nodes | |
public void connectNode(Node start,Node end) | |
{ | |
if(adjMatrix==null) | |
{ | |
size=nodes.size(); | |
adjMatrix=new int[size][size]; | |
} | |
int startIndex=nodes.indexOf(start); | |
int endIndex=nodes.indexOf(end); | |
adjMatrix[startIndex][endIndex]=1; | |
adjMatrix[endIndex][startIndex]=1; | |
} | |
private Node getUnvisitedChildNode(Node n) | |
{ | |
int index=nodes.indexOf(n); | |
int j=0; | |
while(j<size) | |
{ | |
if(adjMatrix[index][j]==1 && ((Node)nodes.get(j)).visited==false) | |
{ | |
return (Node)nodes.get(j); | |
} | |
j++; | |
} | |
return null; | |
} | |
//BFS traversal of a tree is performed by the bfs() function | |
public void bfs() | |
{ | |
//BFS uses Queue data structure | |
Queue q=new LinkedList(); | |
q.add(this.rootNode); | |
printNode(this.rootNode); | |
rootNode.visited=true; | |
while(!q.isEmpty()) | |
{ | |
Node n=(Node)q.remove(); | |
Node child=null; | |
while((child=getUnvisitedChildNode(n))!=null) | |
{ | |
child.visited=true; | |
printNode(child); | |
q.add(child); | |
} | |
} | |
//Clear visited property of nodes | |
clearNodes(); | |
} | |
//DFS traversal of a tree is performed by the dfs() function | |
public void dfs() | |
{ | |
//DFS uses Stack data structure | |
Stack s=new Stack(); | |
s.push(this.rootNode); | |
rootNode.visited=true; | |
printNode(rootNode); | |
while(!s.isEmpty()) | |
{ | |
Node n=(Node)s.peek(); | |
Node child=getUnvisitedChildNode(n); | |
if(child!=null) | |
{ | |
child.visited=true; | |
printNode(child); | |
s.push(child); | |
} | |
else | |
{ | |
s.pop(); | |
} | |
} | |
//Clear visited property of nodes | |
clearNodes(); | |
} | |
//Utility methods for clearing visited property of node | |
private void clearNodes() | |
{ | |
int i=0; | |
while(i<size) | |
{ | |
Node n=(Node)nodes.get(i); | |
n.visited=false; | |
i++; | |
} | |
} | |
//Utility methods for printing the node's label | |
private void printNode(Node n) | |
{ | |
System.out.print(n.label+" "); | |
} | |
} | |
public class Main { | |
/** | |
* @param args | |
*/ | |
public static void main(String[] args) | |
{ | |
//Lets create nodes as given as an example in the article | |
Node nA=new Node('A'); | |
Node nB=new Node('B'); | |
Node nC=new Node('C'); | |
Node nD=new Node('D'); | |
Node nE=new Node('E'); | |
Node nF=new Node('F'); | |
//Create the graph, add nodes, create edges between nodes | |
Graph g=new Graph(); | |
g.addNode(nA); | |
g.addNode(nB); | |
g.addNode(nC); | |
g.addNode(nD); | |
g.addNode(nE); | |
g.addNode(nF); | |
g.setRootNode(nA); | |
g.connectNode(nA,nB); | |
g.connectNode(nA,nC); | |
g.connectNode(nA,nD); | |
g.connectNode(nB,nE); | |
g.connectNode(nB,nF); | |
g.connectNode(nC,nF); | |
//Perform the traversal of the graph | |
System.out.println("DFS Traversal of a tree is ------------->"); | |
g.dfs(); | |
System.out.println("\nBFS Traversal of a tree is ------------->"); | |
g.bfs(); | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment