Union-find

public static int find(int node)
	{
		if(node == parent[node])
		{
			return node;
		}
		
		return parent[node] = find(parent[node]);
	}
	
	public static void union(int from, int to)
	{
		from = find(from);
		to = find(to);
		
		if(from < to)
		{
			parent[to] = parent[from];
		}
		else
		{
			parent[from] = parent[to];
		}
	}