234 lines
8.8 KiB
Java
234 lines
8.8 KiB
Java
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import java.util.HashSet;
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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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import java.util.Set;
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import java.util.Stack;
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public class BiconnectedGraph
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{
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private Queue<Integer> queue;
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private Stack<Integer> stack;
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private int numberOfNodes;
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private Set<Integer> articulationPoints;
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private int[] parent;
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private int[] visited;
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private int[][] adjacencyMatrix;
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public BiconnectedGraph(int numberOfNodes)
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{
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queue = new LinkedList<Integer>();
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this.numberOfNodes = numberOfNodes;
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this.stack = new Stack<Integer>();
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this.articulationPoints = new HashSet<Integer>();
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this.parent = new int[numberOfNodes + 1];
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this.visited = new int[numberOfNodes + 1];
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this.adjacencyMatrix = new int[numberOfNodes + 1][numberOfNodes + 1];
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}
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private boolean bfs(int adjacency_matrix[][], int source)
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{
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boolean connected = true;
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int number_of_nodes = adjacency_matrix[source].length - 1;
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int[] visited = new int[number_of_nodes + 1];
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int i, element;
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visited[source] = 1;
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queue.add(source);
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while (!queue.isEmpty())
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{
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element = queue.remove();
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i = element;
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while (i <= number_of_nodes)
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{
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if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
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{
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queue.add(i);
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visited[i] = 1;
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}
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i++;
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}
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}
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for (int vertex = 1; vertex <= number_of_nodes; vertex++)
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{
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if (visited[vertex] == 1)
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{
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continue;
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}
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else
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{
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connected = false;
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break;
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}
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}
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return connected;
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}
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private int numberOfArticulationPoint(int adjacencyMatrix[][], int source)
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{
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int children = 0;
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int element, destination;
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stack.push(source);
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visited[source] = 1;
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for (int sourceVertex = 1; sourceVertex <= numberOfNodes; sourceVertex++)
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{
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for (int destinationVertex = 1; destinationVertex <= numberOfNodes; destinationVertex++)
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{
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this.adjacencyMatrix[sourceVertex][destinationVertex]
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= adjacencyMatrix[sourceVertex][destinationVertex];
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}
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}
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while (!stack.isEmpty())
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{
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element = stack.peek();
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destination = element;
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while (destination <= numberOfNodes)
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{
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if (this.adjacencyMatrix[element][destination] == 1 && visited[destination] == 0)
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{
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stack.push(destination);
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visited[destination] = 1;
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parent[destination] = element;
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if (element == source)
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{
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children++;
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}
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if (!isLeaf(this.adjacencyMatrix, destination))
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{
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if (children > 1)
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{
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articulationPoints.add(source);
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}
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if(isArticulationPoint(this.adjacencyMatrix, destination))
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{
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articulationPoints.add(destination);
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}
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}
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element = destination;
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destination = 1;
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continue;
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}
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destination++;
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}
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stack.pop();
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}
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return articulationPoints.size();
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}
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public boolean isArticulationPoint(int adjacencyMatrix[][], int root)
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{
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int explored[] = new int[numberOfNodes + 1];
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Stack<Integer> stack = new Stack<Integer>();
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stack.push(root);
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int element = 0,destination = 0;
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while(!stack.isEmpty())
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{
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element = stack.peek();
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destination = 1;
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while (destination <= numberOfNodes)
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{
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if ( element != root)
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{
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if (adjacencyMatrix[element][destination] == 1 && visited[destination] == 1)
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{
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if (this.stack.contains(destination))
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{
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if (destination <= parent[root])
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{
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return false;
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}
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return true;
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}
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}
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}
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if ((adjacencyMatrix[element][destination] == 1 && explored[destination] == 0 )
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&& visited[destination] == 0)
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{
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stack.push(destination);
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explored[destination] = 1;
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adjacencyMatrix[destination][element] = 0;
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element = destination;
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destination = 1;
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continue;
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}
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destination++;
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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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private boolean isLeaf(int adjacencyMatrix[][], int node)
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{
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boolean isLeaf = true;
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for (int vertex = 1; vertex <= numberOfNodes; vertex++)
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{
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if (adjacencyMatrix[node][vertex] == 1 && visited[vertex] == 1)
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{
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isLeaf = true;
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}
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else if (adjacencyMatrix[node][vertex] == 1 && visited[vertex] == 0)
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{
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isLeaf = false;
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break;
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}
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}
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return isLeaf;
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}
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public boolean isBiconnected(int adjacencyMatrix[][], int source)
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{
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boolean biconnected = false;
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if (bfs(adjacencyMatrix, source) && numberOfArticulationPoint(adjacencyMatrix, source) == 0)
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{
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biconnected = true;
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}
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return biconnected;
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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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for (int j = 1; j <= number_of_nodes; j++)
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adjacency_matrix[i][j] = scanner.nextInt();
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System.out.println("Enter the source for the graph");
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source = scanner.nextInt();
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BiconnectedGraph biconnectedGraph = new BiconnectedGraph(number_of_nodes);
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if (biconnectedGraph.isBiconnected(adjacency_matrix, source))
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{
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System.out.println("The Given Graph is BiConnected");
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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 BiConnected");
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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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5
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Enter the adjacency matrix
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0 1 1 1 0
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1 0 1 0 0
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1 1 0 0 1
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1 0 0 0 1
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0 0 1 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 BiConnected
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