123 lines
4.6 KiB
Java
123 lines
4.6 KiB
Java
/*This is a java program to check whether graph contains Eulerian Cycle. The criteran Euler suggested,
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1. If graph has no odd degree vertex, there is at least one Eulerian Circuit.
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2. If graph as two vertices with odd degree, there is no Eulerian Circuit but at least one Eulerian Path.
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3. If graph has more than two vertices with odd degree, there is no Eulerian Circuit or Eulerian Path.*/
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import java.util.InputMismatchException;
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import java.util.Scanner;
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public class UndirectedEulerianCircuit
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{
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private int[][] adjacencyMatrix;
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private int numberOfNodes;
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public UndirectedEulerianCircuit(int numberOfNodes, int[][] adjacencyMatrix)
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{
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this.numberOfNodes = numberOfNodes;
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this.adjacencyMatrix = new int[numberOfNodes + 1][numberOfNodes + 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] = adjacencyMatrix[sourceVertex][destinationVertex];
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}
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}
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}
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public int degree(int vertex)
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{
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int degree = 0;
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for (int destinationvertex = 1; destinationvertex <= numberOfNodes; destinationvertex++)
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{
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if (adjacencyMatrix[vertex][destinationvertex] == 1
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|| adjacencyMatrix[destinationvertex][vertex] == 1)
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{
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degree++;
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}
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}
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return degree;
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}
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public int countOddDegreeVertex()
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{
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int count = 0;
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for (int node = 1; node <= numberOfNodes; node++)
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{
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if ((degree(node) % 2) != 0)
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{
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count++;
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}
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}
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return count;
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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;
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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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// make the graph undirected
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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
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&& 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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UndirectedEulerPath path = new UndirectedEulerPath(number_of_nodes,
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adjacency_matrix);
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int count = path.countOddDegreeVertex();
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if (count == 0)
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{
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System.out
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.println("As the graph has no odd degree vertex, there is at least one Eulerian Circuit.");
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}
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else if (count == 2)
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{
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System.out
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.println("As the graph as two vertices with odd degree, there is no Eulerian Circuit but at least one Eulerian Path.");
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}
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else
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{
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System.out
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.println("As the graph has more than two vertices with odd degree, there is no Eulerian Circuit or Eulerian Path.");
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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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6
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Enter the adjacency matrix
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0 1 0 0 0 0
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1 0 1 1 0 0
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0 1 0 0 0 1
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0 1 0 0 1 1
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0 0 0 1 0 1
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0 0 1 1 1 0
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As the graph has more than two vertices with odd degree, there is no Eulerian Circuit or Eulerian Path. |