public static void main(String[] args) {
try {
Scanner scanner = new Scanner(new FileInputStream("graph.txt"));
int v = Integer.parseInt(scanner.nextLine());
int source = Integer.parseInt(scanner.nextLine());
int sink = Integer.parseInt(scanner.nextLine());
ListGraph g = new ListGraph(v, source, sink);
while (scanner.hasNext()) {
String edgeLine = scanner.nextLine();
String[] components = edgeLine.split("\\s+");
assert components.length == 3;
int i = Integer.parseInt(components[0]);
int j = Integer.parseInt(components[1]);
int capacity = Integer.parseInt(components[2]);
g.addEdge(i, j, capacity);
}
System.out.println("Original matrix");
g.print();
ListGraph.maxFlow(g);
g.print();
} catch (FileNotFoundException e) {
System.err.println(e.toString());
System.exit(1);
}
}
public static void maxFlow(ListGraph g) {
ListGraph residualG = g.residualGraph();
LinkedList<DirEdge> path = residualG.getFlowPath();
while (path != null) {
// System.out.println("Got path");
int minCapacity = ListGraph.minCapacityInPath(path);
assert minCapacity > 0;
// augment every edge on the path in the original graph
int head = g.getSource();
ListIterator it = path.listIterator();
while (it.hasNext()) {
DirEdge rEdge = (DirEdge) it.next();
int tail = rEdge.end;
DirEdge e = g.getEdge(head, tail);
e.flow += minCapacity;
// System.out.println("Augmenting (" + head + "," + tail + ") to be " + e.flow);
head = tail;
}
residualG = g.residualGraph();
// System.out.println("g:");
// g.print();
// System.out.println("Residual graph:");
// residualG.print();
path = residualG.getFlowPath();
}
}
public ListGraph residualGraph() {
ListGraph residualG = new ListGraph(getNumNodes(), this.source, this.sink);
for (int i = 0; i < v; i++) {
ListIterator it = edges.get(i).listIterator();
while (it.hasNext()) {
DirEdge edge = (DirEdge) it.next();
int leftCapacity = edge.capacity - edge.flow;
if (leftCapacity > 0) residualG.addEdge(i, edge.end, leftCapacity);
if (edge.flow > 0)
residualG.addEdge(edge.end, i, edge.flow); // add the reverse direction capacity
}
}
return residualG;
}
