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dfs.java
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63 lines (55 loc) · 1.72 KB
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import java.util.*;
/**
* Implementation of a Depth First Search
*
* @author Unknown
*
*/
public class dfs{
/**
* Implementation in code of a DFS
*
* @param a structure to be DFS'ed
* @param vertices The vertices
* @param source The source
*/
public static void dfsImplement(byte [][] a,int vertices,int source){ //passing adjacency matrix and no of vertices
byte []b=new byte[vertices]; //flag container containing status of each vertices
Arrays.fill(b,(byte)-1); //status initialization
/* code status
-1 = ready
0 = waiting
1 = processed */
Stack st=new Stack(vertices); //operational stack
st.push(source); //assigning source
while(!st.isEmpty()){
b[st.peek()]=(byte)0; //assigning waiting status
System.out.println(st.peek());
int pop=st.pop();
b[pop]=(byte)1; //assigning processed status
for(int i=0;i<vertices;i++){
if(a[pop][i]!=0 && b[i]!=(byte)0 && b[i]!=(byte)1 ){
st.push(i);
b[i]=(byte)0; //assigning waiting status
}}}
}
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String args[]){
Scanner in=new Scanner(System.in);
int vertices=in.nextInt(),source=in.nextInt();
byte [][]a=new byte [vertices][vertices];
//initially all elements of a are initialized with value zero
for(int i=0;i<vertices;i++){
int size =in.nextInt();
for(int j=0;j<size;j++){
a[i][in.nextInt()]=1; //taking adjacency entries by assigning 1
}
}
dfsImplement(a,vertices,source); //function call
in.close();
}
}