63 lines
1.8 KiB
Java
63 lines
1.8 KiB
Java
import java.util.*;
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/**
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* Implementation of a Breadth First Search
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*
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* @author Unknown
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*
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*/
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public class BFS{
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/**
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* The BFS implemented in code to use.
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*
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* @param a Structure to perform the search on a graph, adjacency matrix etc.
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* @param vertices The vertices to use
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* @param source The Source
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*/
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public static void bfsImplement(byte [][] a,int vertices,int source){ //passing adjacency matrix and no of vertices
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byte []b=new byte[vertices]; //flag container containing status of each vertices
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Arrays.fill(b,(byte)-1); //status initialization
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/* code status
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-1 = ready
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0 = waiting
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1 = processed */
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Stack st = new Stack(vertices); //operational stack
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st.push(source); //assigning source
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while(!st.isEmpty()){
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b[st.peek()]=(byte)0; //assigning waiting status
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System.out.println(st.peek());
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int pop=st.peek();
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b[pop]=(byte)1; //assigning processed status
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st.pop(); //removing head of the queue
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for(int i=0;i<vertices;i++){
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if(a[pop][i]!=0 && b[i]!=(byte)0 && b[i]!=(byte)1 ){
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st.push(i);
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b[i]=(byte)0; //assigning waiting status
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}}}
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}
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/**
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* The main method
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*
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* @param args Command line arguments
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*/
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public static void main(String args[]){
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Scanner in=new Scanner(System.in);
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int vertices=in.nextInt(),source=in.nextInt();
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byte [][]a=new byte [vertices][vertices];
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//initially all elements of a are initialized with value zero
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for(int i=0;i<vertices;i++){
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int size =in.nextInt();
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for(int j=0;j<size;j++){
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a[i][in.nextInt()]=1; //taking adjacency entries by assigning 1
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}
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}
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bfsImplement(a,vertices,source); //function call
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in.close();
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}
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}
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