This is a java program find the edge connectivity of the given graph. The edge connectivity simply means, number of bridges in a graph, bridges are edges when removed makes the graph disconnected.
Here is the source code of the Java Program to Find the Edge Connectivity of a Graph. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.
// Number of bridges in a graph package com.maixuanviet.graph; import java.util.Iterator; import java.util.NoSuchElementException; import java.util.Scanner; import java.util.Stack; class ECBag<Item> implements Iterable<Item> { private int N; // number of elements in ECBag private Node<Item> first; // beginning of ECBag // helper linked list class private static class Node<Item> { private Item item; private Node<Item> next; } public ECBag() { first = null; N = 0; } public boolean isEmpty() { return first == null; } public int size() { return N; } public void add(Item item) { Node<Item> oldfirst = first; first = new Node<Item>(); first.item = item; first.next = oldfirst; N++; } public Iterator<Item> iterator() { return new ListIterator<Item>(first); } // an iterator, doesn't implement remove() since it's optional @SuppressWarnings("hiding") private class ListIterator<Item> implements Iterator<Item> { private Node<Item> current; public ListIterator(Node<Item> first) { current = first; } public boolean hasNext() { return current != null; } public void remove() { throw new UnsupportedOperationException(); } public Item next() { if (!hasNext()) throw new NoSuchElementException(); Item item = current.item; current = current.next; return item; } } } class BridgeGraph { private final int V; private int E; private ECBag<Integer>[] adj; @SuppressWarnings("unchecked") public BridgeGraph(int V) { if (V < 0) throw new IllegalArgumentException( "Number of vertices must be nonnegative"); this.V = V; this.E = 0; adj = (ECBag<Integer>[]) new ECBag[V]; for (int v = 0; v < V; v++) { adj[v] = new ECBag<Integer>(); } System.out.println("Enter the number of edges: "); Scanner sc = new Scanner(System.in); int E = sc.nextInt(); if (E < 0) { sc.close(); throw new IllegalArgumentException( "Number of edges must be nonnegative"); } for (int i = 0; i < E; i++) { int v = sc.nextInt(); int w = sc.nextInt(); addEdge(v, w); } sc.close(); } public BridgeGraph(BridgeGraph G) { this(G.V()); this.E = G.E(); for (int v = 0; v < G.V(); v++) { // reverse so that adjacency list is in same order as original Stack<Integer> reverse = new Stack<Integer>(); for (int w : G.adj[v]) { reverse.push(w); } for (int w : reverse) { adj[v].add(w); } } } public int V() { return V; } public int E() { return E; } public void addEdge(int v, int w) { if (v < 0 || v >= V) throw new IndexOutOfBoundsException(); if (w < 0 || w >= V) throw new IndexOutOfBoundsException(); E++; adj[v].add(w); adj[w].add(v); } public Iterable<Integer> adj(int v) { if (v < 0 || v >= V) throw new IndexOutOfBoundsException(); return adj[v]; } public String toString() { StringBuilder s = new StringBuilder(); String NEWLINE = System.getProperty("line.separator"); s.append(V + " vertices, " + E + " edges " + NEWLINE); for (int v = 0; v < V; v++) { s.append(v + ": "); for (int w : adj[v]) { s.append(w + " "); } s.append(NEWLINE); } return s.toString(); } } public class EdgeConnectivity { private int bridges; // number of bridges private int cnt; // counter private int[] pre; // pre[v] = order in which dfs examines v private int[] low; // low[v] = lowest preorder of any vertex connected // to v public EdgeConnectivity(BridgeGraph G) { low = new int[G.V()]; pre = new int[G.V()]; for (int v = 0; v < G.V(); v++) low[v] = -1; for (int v = 0; v < G.V(); v++) pre[v] = -1; for (int v = 0; v < G.V(); v++) if (pre[v] == -1) dfs(G, v, v); } public int components() { return bridges + 1; } private void dfs(BridgeGraph G, int u, int v) { pre[v] = cnt++; low[v] = pre[v]; for (int w : G.adj(v)) { if (pre[w] == -1) { dfs(G, v, w); low[v] = Math.min(low[v], low[w]); if (low[w] == pre[w]) { // System.out.println(v + "-" + w + " is a bridge"); bridges++; } } // update low number - ignore reverse of edge leading to v else if (w != u) low[v] = Math.min(low[v], pre[w]); } } public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter the number of vertices: "); BridgeGraph G = new BridgeGraph(sc.nextInt()); System.out.println(G); EdgeConnectivity bridge = new EdgeConnectivity(G); System.out.println("Edge Connectivity: " + bridge.bridges); sc.close(); } }
Output:
$ javac EdgeConnectivity.java $ java EdgeConnectivity Enter the number of vertices: 6 Enter the number of edges: 7 0 1 1 2 1 3 3 4 4 5 5 3 5 2 6 vertices, 7 edges 0: 1 1: 3 2 0 2: 5 1 3: 5 4 1 4: 5 3 5: 2 3 4 Edge Connectivity: 1
Related posts:
Java Program to Implement Sieve Of Atkin
Java Program to Solve any Linear Equation in One Variable
Java Program to Implement Min Hash
Java Program to Implement Graham Scan Algorithm to Find the Convex Hull
Spring MVC Setup with Kotlin
Testing in Spring Boot
Debug a JavaMail Program
ClassNotFoundException vs NoClassDefFoundError
Using the Not Operator in If Conditions in Java
Java Program to Generate All Possible Combinations of a Given List of Numbers
Creating Docker Images with Spring Boot
Spring Boot: Customize the Jackson ObjectMapper
Mệnh đề if-else trong java
Hướng dẫn Java Design Pattern – Facade
Hướng dẫn Java Design Pattern – State
Spring Boot - Application Properties
Java Stream Filter with Lambda Expression
The XOR Operator in Java
Lớp Collectors trong Java 8
Introduction to Spring Method Security
Java Program to Implement Sorted Circularly Singly Linked List
Java Program to Implement Hash Tables with Linear Probing
Java Program to Implement Hash Tables Chaining with Binary Trees
A Guide to BitSet in Java
Map Serialization and Deserialization with Jackson
Java Program to Implement Self organizing List
The Thread.join() Method in Java
Phương thức forEach() trong java 8
Giới thiệu Google Guice – Aspect Oriented Programming (AOP)
Java Program to Perform Stooge Sort
Introduction to PCollections
Giới thiệu HATEOAS