116 lines
4.4 KiB
Java
116 lines
4.4 KiB
Java
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/*This Java program is to check whether graph is bipartite using dfs. 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.Scanner;
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import java.util.Stack;
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public class BipartiteDfs
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{
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private int numberOfVertices;
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private Stack<Integer> stack;
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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 BipartiteDfs(int numberOfVertices)
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{
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this.numberOfVertices = numberOfVertices;
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stack = new Stack<Integer>();
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}
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public boolean isBipartite(int adjacencyMartix[][], 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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stack.push(source);
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colored[source] = RED;
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int element = source;
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int neighbours = source;
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while (!stack.empty())
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{
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element = stack.peek();
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neighbours = element;
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while (neighbours <= numberOfVertices)
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{
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if (adjacencyMartix[element][neighbours] == 1&& colored[neighbours] == colored[element])
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{
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return false;
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}
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if (adjacencyMartix[element][neighbours] == 1 && colored[neighbours] == NO_COLOR)
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{
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colored[neighbours] = (colored[element] == RED) ? BLUE : RED;
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stack.push(neighbours);
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element = neighbours;
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neighbours = 1;
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continue;
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}
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neighbours++;
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}
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stack.pop();
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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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BipartiteDfs bipartiteDfs = new BipartiteDfs(number_of_nodes);
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if (bipartiteDfs.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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