Java implementation to find lowest common ancestor of in a Binary Tree

LCAInBT.java

// Java implementation to find lowest common ancestor of
// n1 and n2 using one traversal of binary tree
// It also handles cases even when n1 and n2 are not there in Tree
// It handles the case when both the nodes are present in same subtree(see the 2,4 example below)
// The basic idea is to start searching from the lead node.
class Node
{
	int data;
	Node left, right;

	public Node(int item)
	{
		data = item;
		left = right = null;
	}
}

public class BinaryTree
{
	// Root of the Binary Tree
	Node root;
	static boolean v1 = false, v2 = false;

	// This function returns pointer to LCA of two given
	// values n1 and n2.
	// v1 is set as true by this function if n1 is found
	// v2 is set as true by this function if n2 is found
	Node findLCAUtil(Node node, int n1, int n2)
	{
		// Base case
		if (node == null)
			return null;

		// Look for keys in left and right subtrees
		Node left_lca = findLCAUtil(node.left, n1, n2);
		Node right_lca = findLCAUtil(node.right, n1, n2);
		
		// If either n1 or n2 matches with root's key, report the presence
		// by setting v1 or v2 as true and return root (Note that if a key
		// is ancestor of other, then the ancestor key becomes LCA)
		if (node.data == n1)
		{
			v1 = true;
			return node;
		}
		if (node.data == n2)
		{
			v2 = true;
			return node;
		}

		// If both of the above calls return Non-NULL, then one key
		// is present in once subtree and other is present in other,
		// So this node is the LCA
		if (left_lca != null && right_lca != null)
			return node;

		// Otherwise check if left subtree or right subtree is LCA
		return (left_lca != null) ? left_lca : right_lca;
	}

	// Finds lca of n1 and n2 under the subtree rooted with 'node'
	Node findLCA(int n1, int n2)
	{
		// Initialize n1 and n2 as not visited
		v1 = false;
		v2 = false;

		// Find lca of n1 and n2 using the technique discussed above
		Node lca = findLCAUtil(root, n1, n2);

		// Return LCA only if both n1 and n2 are present in tree
		if (v1 && v2)
			return lca;

		// Else return NULL
		return null;
	}

	/* Driver program to test above functions */
	public static void main(String args[])
	{
		BinaryTree tree = new BinaryTree();
		tree.root = new Node(1);
		tree.root.left = new Node(2);
		tree.root.right = new Node(3);
		tree.root.left.left = new Node(4);
		tree.root.left.right = new Node(5);
		tree.root.right.left = new Node(6);
		tree.root.right.right = new Node(7);

		Node lca = tree.findLCA(4, 2);
		if (lca != null)
			System.out.println("LCA(4, 2) = " + lca.data);
		else
			System.out.println("Keys are not present");


		lca = tree.findLCA(10, 4);
		if (lca != null)
			System.out.println("LCA(2, 4) = " + lca.data);
		else
			System.out.println("Keys are not present");
	}
}