Create DFSGraph.java

Author: Blooverh

DataAndAlgoL/Chpt9GraphAlgorithms/DFSGraph.java

@@ -0,0 +1,79 @@
+package DataAndAlgoL.Chpt9GraphAlgorithms;
+
+import java.util.Stack;
+
+class Vertex{
+    public char label;
+    public boolean visited;
+    public Vertex(char lab){
+        label=lab;
+        visited=false;
+    }
+}
+public class DFSGraph {
+    final int maxVertices=20; //max number of vertices in the graph
+    Vertex[] vertexList; //array of vertices 
+    int[][] adjMatrix; //matrix that will hold the vertices 
+    int vertexCount;
+    Stack theStack;
+
+
+    public DFSGraph(){
+        vertexList= new Vertex[maxVertices]; //new array of vertices of size maxVertices (20)
+        adjMatrix= new int[maxVertices][maxVertices];// matrix that will contain the vertices with matrix size 20x20 
+        vertexCount=0; 
+        for(int i=0; i< maxVertices; i++){
+            for(int j=0; j<maxVertices; j++){
+                adjMatrix[i][j]=0; //populate the entire matrix with value 0 for each cell in row and column
+            }
+        }
+
+        theStack= new Stack();
+
+    }
+
+    public void addVertex(char lab){
+        vertexList[vertexCount++]= new Vertex(lab); //each char lab will be put in vertex list starting from 0 (vertexCount)
+    }
+
+    //creates an edge with value 1 for the position we want to add the edge
+    public void addEdge(int start, int end){
+        adjMatrix[start][end]=1;
+        adjMatrix[end][start]=1;
+    }
+
+    public void displayVertex(int v){
+        System.out.println(vertexList[v].label); //displays the char value of the vertex at position v 
+    }
+
+    public void dfs(){
+        vertexList[0].visited=true;
+        displayVertex(0);
+        theStack.push(0);
+        while(!theStack.isEmpty()){
+            int v=getAdjUnvisitedVertex((int) theStack.peek());
+            if(v ==-1){
+                theStack.pop();
+            }else{
+                vertexList[v].visited=true;
+                displayVertex(v);
+                theStack.push(v);
+            }
+        }
+
+        //reset flags
+        for(int i=0; i<vertexCount; i++){
+            vertexList[i].visited=false;
+        }
+    }
+
+    public int getAdjUnvisitedVertex(int v){
+        for(int i=0; i< vertexCount; i++){
+            if(adjMatrix[v][i]==1 && vertexList[i].visited==false){
+                return i;
+            }
+        }
+
+        return -1;
+    }
+}