algorithms/Java/DisjointSetUnion.java at master · AASF-IIITM/algorithms · GitHub

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class GFG
{
static int N = 100010;

static class Edge
{
	int u, v;

	public Edge(int u, int v)
	{
		this.u = u;
		this.v = v;
	}
}


static int []id = new int[N];
static int []sz = new int[N];


static int Root(int idx)
{
	int i = idx;

	while(i != id[i])
	{
		id[i] = id[id[i]];
		i = id[i];
	}
	return i;
}


static void Union(int a, int b)
{
	int i = Root(a), j = Root(b);

	if (i != j)
	{
		if(sz[i] >= sz[j])
		{
			id[j] = i;
			sz[i] += sz[j];
			sz[j] = 0;
		}
		else
		{
			id[i] = j;
			sz[j] += sz[i];
			sz[i] = 0;
		}
	}
}


static void UnionUtil(Edge e[], int W[], int q)
{
	for(int i = 0; i < q; i++)
	{

		int u, v;
		u = e[i].u;
		v = e[i].v;


		u--;
		v--;


		if(W[u] % 2 == 0 && W[v] % 2 == 0)
			Union(u, v);
	}
}


static int findMax(int n, int W[])
{
	int maxi = 0;
	for(int i = 1; i < n; i++)
		if(W[i] % 2 == 0)
			maxi = Math.max(maxi, sz[i]);

	return maxi;
}


public static void main(String[] args)
{


	int W[] = {1, 2, 6, 4, 2, 0, 3};


	int n = W.length;


	for(int i = 0; i < n; i++)
	{
		id[i] = i;
		sz[i] = 1;
	}

	Edge e[] = {new Edge(1, 2), new Edge(1, 3),
				new Edge(2, 4), new Edge(2, 5),
				new Edge(4, 6), new Edge(6, 7)};

	int q = e.length;

	UnionUtil(e, W, q);


	int maxi = findMax(n, W);

	System.out.printf("Maximum size of the subtree with ");
	System.out.printf("even weighted nodes = %d\n", maxi);
}
}