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2 a networkflow
2 a networkflow
2 a networkflow
2 a networkflow
2 a networkflow
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2 a networkflow

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network flow example program

network flow example program

Published in: Technology, Education
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  1. EXP.2 A- IMPLEMENTATION AND APPLICATION OF NETWORK FLOW CODE: import import import import import import import java.util.ArrayList; java.util.HashSet; java.util.Iterator; java.util.LinkedList; java.util.Queue; java.util.Scanner; java.util.Set; public class NetworkFlowProb { private int[] parent; private Queue<Integer> queue; private int numberOfVertices; private boolean[] visited; private Set<Pair> cutSet; private ArrayList<Integer> reachable; private ArrayList<Integer> unreachable; public NetworkFlowProb (int numberOfVertices) { this.numberOfVertices = numberOfVertices; this.queue = new LinkedList<Integer>(); parent = new int[numberOfVertices + 1]; visited = new boolean[numberOfVertices + 1]; cutSet = new HashSet<Pair>(); reachable = new ArrayList<Integer>(); unreachable = new ArrayList<Integer>(); } public boolean bfs (int source, int goal, int graph[][]) { boolean pathFound = false; int destination, element; for (int vertex = 1; vertex <= numberOfVertices; vertex++) { parent[vertex] = -1; visited[vertex] = false; } queue.add(source); parent[source] = -1; visited[source] = true; while (!queue.isEmpty()) { element = queue.remove();
  2. destination = 1; while (destination <= numberOfVertices) { if (graph[element][destination] > 0 && !visited[destination]) { parent[destination] = element; queue.add(destination); visited[destination] = true; } destination++; } } if (visited[goal]) { pathFound = true; } return pathFound; } public int networkFlow (int graph[][], int source, int destination) { int u, v; int maxFlow = 0; int pathFlow; int[][] residualGraph = new int[numberOfVertices + 1][numberOfVertices + 1]; for (int sourceVertex = 1; sourceVertex <= numberOfVertices; sourceVertex++) { for (int destinationVertex = 1; destinationVertex <= numberOfVertices; destinationVertex++) { residualGraph[sourceVertex][destinationVertex] = graph[sourceVertex][destinationVertex]; } } /*max flow*/ while (bfs(source, destination, residualGraph)) { pathFlow = Integer.MAX_VALUE; for (v = destination; v != source; v = parent[v]) { u = parent[v]; pathFlow = Math.min(pathFlow, residualGraph[u][v]); } for (v = destination; v != source; v = parent[v]) {
  3. u = parent[v]; residualGraph[u][v] -= pathFlow; residualGraph[v][u] += pathFlow; } maxFlow += pathFlow; } /*calculate the cut set*/ for (int vertex = 1; vertex <= numberOfVertices; vertex++) { if (bfs(source, vertex, residualGraph)) { reachable.add(vertex); } else { unreachable.add(vertex); } } for (int i = 0; i < reachable.size(); i++) { for (int j = 0; j < unreachable.size(); j++) { if (graph[reachable.get(i)][unreachable.get(j)] > 0) { cutSet.add (new Pair(reachable.get(i), unreachable.get(j))); } } } return maxFlow; } public void printCutSet () { Iterator<Pair> iterator = cutSet.iterator(); while (iterator.hasNext()) { Pair pair = iterator.next(); System.out.println(pair.source + "-" + pair.destination); } } public static void main (String...arg) { int[][] graph; int numberOfNodes; int source; int sink; int maxFlow; Scanner scanner = new Scanner(System.in);
  4. System.out.println("Enter the number of nodes"); numberOfNodes = scanner.nextInt(); graph = new int[numberOfNodes + 1][numberOfNodes + 1]; System.out.println("Enter the graph matrix"); for (int sourceVertex = 1; sourceVertex <= numberOfNodes; sourceVertex++) { for (int destinationVertex = 1; destinationVertex <= numberOfNodes; destinationVertex++) { graph[sourceVertex][destinationVertex] = scanner.nextInt(); } } System.out.println("Enter the source of the graph"); source= scanner.nextInt(); System.out.println("Enter the sink of the graph"); sink = scanner.nextInt(); NetworkFlowProb networkFlowProb = new NetworkFlowProb(numberOfNodes); maxFlow = networkFlowProb.networkFlow(graph, source, sink); System.out.println("The Max flow in the graph is " + maxFlow); System.out.println("The Minimum Cut Set in the Graph is "); networkFlowProb.printCutSet(); scanner.close(); } } class Pair { public int source; public int destination; public Pair(int source, int destination) { this.source = source; this.destination = destination; } public Pair() { } }
  5. OUTPUT:

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