This is a java program to find feedback vertex set. This is the set which contains vertices when removed from graph, graph becomes Directed acuclic graph.
Here is the source code of the Java Program to Find a Good Feedback Vertex Set. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.
package com.maixuanviet.hardgraph; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Scanner; class GraphLL { private Map<Integer, List<Integer>> adjacencyList; public GraphLL(int v) { adjacencyList = new HashMap<Integer, List<Integer>>(); for (int i = 1; i <= v; i++) adjacencyList.put(i, new LinkedList<Integer>()); } public void setEdge(int from, int to) { if (to > adjacencyList.size() || from > adjacencyList.size()) System.out.println("The vertices does not exists"); /* * List<Integer> sls = adjacencyList.get(to); * sls.add(from); */ List<Integer> dls = adjacencyList.get(from); dls.add(to); } public List<Integer> getEdge(int to) { /* * if (to > adjacencyList.size()) * { * System.out.println("The vertices does not exists"); * return null; * } */ return adjacencyList.get(to); } public GraphLL checkDAG() { Integer count = 0; Iterator<Integer> iteratorI = this.adjacencyList.keySet().iterator(); Integer size = this.adjacencyList.size() - 1; while (iteratorI.hasNext()) { Integer i = iteratorI.next(); List<Integer> adjList = this.adjacencyList.get(i); if (count == size) { return this; } if (adjList.size() == 0) { count++; Iterator<Integer> iteratorJ = this.adjacencyList.keySet() .iterator(); while (iteratorJ.hasNext()) { Integer j = iteratorJ.next(); List<Integer> li = this.adjacencyList.get(j); if (li.contains(i)) { li.remove(i); } } this.adjacencyList.remove(i); iteratorI = this.adjacencyList.keySet().iterator(); } } return this; } public void printGraph() { System.out.println("The Graph is: "); Iterator<Integer> iterator = this.adjacencyList.keySet().iterator(); while (iterator.hasNext()) { Integer i = iterator.next(); List<Integer> edgeList = this.getEdge(i); if (edgeList.size() != 0) { System.out.print(i); for (int j = 0; j < edgeList.size(); j++) { System.out.print(" -> " + edgeList.get(j)); } System.out.println(); } } } public boolean getFeedbackVertexSet(int v) { boolean flag = false; int[] visited = new int[v + 1]; Iterator<Integer> iterator = this.adjacencyList.keySet().iterator(); System.out.print("The set of vertices in feedback vertex set: "); while (iterator.hasNext()) { Integer i = iterator.next(); List<Integer> list = this.adjacencyList.get(i); visited[i] = 1; if (list.size() != 0) { for (int j = 0; j < list.size(); j++) { if (visited[list.get(j)] == 1) { flag = true; System.out.println(list.get(j) + " "); } else { visited[list.get(j)] = 1; } } } } return flag; } } public class FeedbackVertexSet { public static void main(String args[]) { int v, e, count = 1, to, from; Scanner sc = new Scanner(System.in); GraphLL glist; try { System.out.println("Enter the number of vertices: "); v = sc.nextInt(); System.out.println("Enter the number of edges: "); e = sc.nextInt(); glist = new GraphLL(v); System.out.println("Enter the edges in the graph : <from> <to>"); while (count <= e) { to = sc.nextInt(); from = sc.nextInt(); glist.setEdge(to, from); count++; } glist.printGraph(); GraphLL modified = glist.checkDAG(); if (modified.getFeedbackVertexSet(v) == false) { System.out.println("None"); } } catch (Exception E) { System.out .println("You are trying to access empty adjacency list of a node."); } sc.close(); } }
Output:
Enter the number of vertices: 6 Enter the number of edges: 7 Enter the edges in the graph : <from> <to> 1 2 2 3 2 4 4 5 5 6 6 4 6 3 The Graph is: 1 -> 2 2 -> 3 -> 4 4 -> 5 5 -> 6 6 -> 4 -> 3 The set of vertices in feedback vertex set: 4
Related posts:
Tránh lỗi ConcurrentModificationException trong Java như thế nào?
Java Program to Implement Knight’s Tour Problem
A Quick JUnit vs TestNG Comparison
An Intro to Spring Cloud Task
Sử dụng JDBC API thực thi câu lệnh truy vấn dữ liệu
Spring Boot - Tomcat Deployment
Java Program to Create the Prufer Code for a Tree
Getting the Size of an Iterable in Java
Spring Boot - Hystrix
HashSet trong Java hoạt động như thế nào?
Spring Boot Tutorial – Bootstrap a Simple Application
Java Program to Represent Graph Using Incidence List
Lớp HashMap trong Java
Comparing Arrays in Java
Java Program to Implement HashTable API
Java Program to Check if any Graph is Possible to be Constructed for a Given Degree Sequence
Programmatic Transaction Management in Spring
Create a Custom Exception in Java
Merging Two Maps with Java 8
Java Program to Implement Naor-Reingold Pseudo Random Function
Spring Boot - Unit Test Cases
Spring Boot - Service Components
Spring Autowiring of Generic Types
Java Program to Check Whether an Input Binary Tree is the Sub Tree of the Binary Tree
@Before vs @BeforeClass vs @BeforeEach vs @BeforeAll
The SpringJUnitConfig and SpringJUnitWebConfig Annotations in Spring 5
Java Program to Implement Max Heap
SOAP Web service: Upload và Download file sử dụng MTOM trong JAX-WS
Examine the internal DNS cache
Check If a File or Directory Exists in Java
MyBatis with Spring
Java Program to Implement LinkedHashMap API