public static void Sample_Minimum_Span_Tree()
{
//this example shows how to use disjoint set to solve problem
//this is cost of network in seven nodes A to G
// A B C D E F G
//A - 16 12 21 - - -
//B 16 - - 17 20 - -
//C 12 - - 28 - 31 -
//D 21 17 28 - 18 19 23
//E - 20 - 18 - - 11
//F - - 31 19 - - 27
//G - - - 23 11 27 -
var costList = new[]
{
Tuple.Create('A', 'B', 16),
Tuple.Create('A', 'C', 12),
Tuple.Create('A', 'D', 21),
Tuple.Create('B', 'D', 17),
Tuple.Create('B', 'E', 20),
Tuple.Create('C', 'D', 28),
Tuple.Create('C', 'F', 31),
Tuple.Create('D', 'E', 18),
Tuple.Create('D', 'F', 19),
Tuple.Create('D', 'G', 23),
Tuple.Create('E', 'G', 11),
Tuple.Create('F', 'G', 27)
};
//get current cost
Console.WriteLine("Current cost of network is {0}", costList.Sum(c => c.Item3));
//sort the cost and reconnect the network
//do until you get only one group
var disjoint = new DisjointSet <char>();
var sum = 0;
Console.WriteLine();
foreach (var cost in costList.OrderBy(c => c.Item3))
{
if (!disjoint.IsUnion(cost.Item1, cost.Item2))
{
disjoint.Union(cost.Item1, cost.Item2);
Console.WriteLine("Connect {0} and {1}", cost.Item1, cost.Item2);
sum += cost.Item3;
if (disjoint.SizeOf('A') == 7)
{
break;
}
}
}
Console.WriteLine("Current cost of network is {0}", sum);
}
public static void DisjointSet_SizeOf()
{
//this example shows how to get size of the group from an item
//create disjoint set
var disjoint = new DisjointSet <int>();
disjoint.Union(2, 3);
disjoint.Union(5, 7);
disjoint.Union(11, 13);
disjoint.Union(1, 2);
disjoint.Union(3, 4);
disjoint.Union(5, 6);
//show
foreach (var grp in disjoint)
{
Console.WriteLine(grp.ToString(", "));
}
//use disjoint.SizeOf(item) to get size of the group from an item
Console.WriteLine();
Console.WriteLine("Size of group of {0} is {1}", 1, disjoint.SizeOf(1));
}
