private static void MaxFlow(FlowGraph graph)
{
while (true)
{
var foundPath = false;
var queue = new Queue <int>();
var parentIds = new int[graph.Size()];
for (var i = 0; i < parentIds.Length; i++)
{
parentIds[i] = -1;
}
queue.Enqueue(0);
//bfs
while (queue.Count > 0 && !foundPath)
{
var node = queue.Dequeue();
var ids = graph.GetIds(node);
foreach (var id in ids)
{
var edge = graph.GetEdge(id);
if (edge.Flow < edge.Capacity && parentIds[edge.To] == -1)
{
if (edge.To == edge.From)
{
continue;
}
parentIds[edge.To] = id;
if (edge.To == graph.Size() - 1)
{
foundPath = true;
break;
}
queue.Enqueue(edge.To);
}
}
}
if (!foundPath)
{
break;
}
//find the value of the flow
var to = graph.Size() - 1;
var minCapacity = -1;
while (to != 0)
{
var id = parentIds[to];
var edge = graph.GetEdge(id);
if (minCapacity == -1 || (edge.Capacity - edge.Flow) < minCapacity)
{
minCapacity = edge.Capacity - edge.Flow;
}
to = edge.From;
}
to = graph.Size() - 1;
while (to != 0)
{
var id = parentIds[to];
var edge = graph.GetEdge(id);
graph.AddFlow(id, minCapacity);
to = edge.From;
}
}
}