112 lines
4.2 KiB
Java
112 lines
4.2 KiB
Java
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/*This Java program is to check whether graph is bipartite using bfs. In the mathematical field of graph theory, a bipartite graph (or bigraph) is a graph whose vertices can be divided into two disjoint sets and such that every edge connects a vertex in to one in that is, and are each independent sets. Equivalently, a bipartite graph is a graph that does not contain any odd-length cycles.*/
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import java.util.InputMismatchException;
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import java.util.LinkedList;
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import java.util.Queue;
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import java.util.Scanner;
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public class BipartiteBfs
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{
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private int numberOfVertices;
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private Queue<Integer> queue;
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public static final int NO_COLOR = 0;
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public static final int RED = 1;
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public static final int BLUE = 2;
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public BipartiteBfs(int numberOfVertices)
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{
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this.numberOfVertices = numberOfVertices;
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queue = new LinkedList<Integer>();
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}
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public boolean isBipartite(int adjacencyMatrix[][], int source)
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{
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int[] colored = new int[numberOfVertices + 1];
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for (int vertex = 1; vertex <= numberOfVertices; vertex++)
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{
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colored[vertex] = NO_COLOR;
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}
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colored[source] = RED;
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queue.add(source);
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int element, neighbour;
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while (!queue.isEmpty())
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{
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element = queue.remove();
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neighbour = 1;
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while (neighbour <= numberOfVertices)
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{
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if (adjacencyMatrix[element][neighbour] == 1 && colored[element]== colored[neighbour])
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{
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return false;
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}
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if (adjacencyMatrix[element][neighbour] == 1 && colored[neighbour]== NO_COLOR)
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{
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colored[neighbour] = (colored[element] == RED ) ? BLUE :RED;
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queue.add(neighbour);
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}
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neighbour++;
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}
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}
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return true;
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}
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public static void main(String... arg)
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{
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int number_of_nodes, source;
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Scanner scanner = null;
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try
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{
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System.out.println("Enter the number of nodes in the graph");
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scanner = new Scanner(System.in);
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number_of_nodes = scanner.nextInt();
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int adjacency_matrix[][] = new int[number_of_nodes + 1][number_of_nodes + 1];
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System.out.println("Enter the adjacency matrix");
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for (int i = 1; i <= number_of_nodes; i++)
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{
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for (int j = 1; j <= number_of_nodes; j++)
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{
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adjacency_matrix[i][j] = scanner.nextInt();
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}
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}
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for (int i = 1; i <= number_of_nodes; i++)
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{
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for (int j = 1; j <= number_of_nodes; j++)
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{
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if(adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
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{
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adjacency_matrix[j][i] = 1;
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}
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}
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}
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System.out.println("Enter the source for the graph");
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source = scanner.nextInt();
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BipartiteBfs bipartiteBfs = new BipartiteBfs(number_of_nodes);
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if (bipartiteBfs.isBipartite(adjacency_matrix, source))
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{
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System.out.println("The given graph is bipartite");
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}
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else
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{
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System.out.println("The given graph is not bipartite");
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}
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}
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catch (InputMismatchException inputMismatch)
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{
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System.out.println("Wrong Input format");
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}
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scanner.close();
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}
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}
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/*
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Enter the number of nodes in the graph
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4
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Enter the adjacency matrix
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0 1 0 1
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1 0 1 0
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0 1 0 1
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1 0 1 0
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Enter the source for the graph
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1
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The given graph is bipartite
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