public static bool colorBFS(Node n)
{
Color colorToPaint; //Actual color to paint.
Stack<Node> s = new Stack<Node>();
if(n.color == Color.None)
n.color = Color.Blue;
s.Push(n);
while (s.Count != 0) {
Node parent = s.Pop();
if (parent.check)
continue;
count++;//keep track of the number of operations done (Testing purposes).
parent.check = true;
if (parent.color == Color.Red)
colorToPaint = Color.Blue;
else
colorToPaint = Color.Red;
bool isImportant = false;
for (int i = 0; i < parent.children.Count; i++) {
Node child = parent.children[i];
isImportant = true;
if (child.color == parent.color)
return false;
if (child.color == Color.None) {
child.importantRelation = true;
child.color = colorToPaint;
s.Push(child);
}
}
if (!parent.importantRelation)
parent.importantRelation = isImportant;
}
return true;
}
static void Main(string[] args)
{
List<Node> tree = new List<Node>();
String[] nums;
nums = Console.ReadLine().Split(' ');
int elems = Convert.ToInt32(nums[0]),restrictions = Convert.ToInt32(nums[1]);
for (int i = 0; i < elems; i++) {
Node n = new Node(i + 1);
tree.Add(n);
}
for (int i = 0; i < restrictions; i++)
{
String[] r = Console.ReadLine().Split(' ');
int a = Convert.ToInt32(r[0]), b = Convert.ToInt32(r[1]);
tree[a - 1].children.Add(tree[b - 1]); //Add to children. Make a directed graph.
}
//Since the graph is not fully connected, better make sure to paint all nodes.
for (int i = 0; i < tree.Count; i++) {
if (!colorBFS(tree[i])) {
Console.WriteLine("No solution found...");
return;
}
}
//Print blue ones:
List<Node> Blues = new List<Node>(), Reds = new List<Node>(),notImportant = new List<Node>();
//
for (int i = 0; i < tree.Count; i++)
{
Node n = tree[i];
if (n.importantRelation)
{
if (n.color == Color.Blue)
Blues.Add(n);
else
Reds.Add(n);
}
else
notImportant.Add(n); //Not important elements are used to play around after important ones have been distributed.
}
for (int i = 0; i < notImportant.Count; i++) {
Node n = notImportant[i];
if (Blues.Count < Reds.Count)
Blues.Add(n);
else
Reds.Add(n);
}
//Sort blues and Reds.
Blues.Sort(delegate (Node n1, Node n2) { return n1.value.CompareTo(n2.value); });
Reds.Sort(delegate (Node n1, Node n2) { return n1.value.CompareTo(n2.value); });
Console.WriteLine(Blues.Count);
for (int i = 0; i < Blues.Count; i++)
{
Node n = Blues[i];
Console.Write(n.value + " ");
}
Console.WriteLine();
Console.WriteLine(Reds.Count);
for (int i = 0; i < Reds.Count; i++)
{
Node n = Reds[i];
Console.Write(n.value + " ");
}
Console.WriteLine();
//Console.WriteLine("Number of ops: " + count);
Console.Read();
}
