floor_and_ceil.java

// Java program to find ceil of a given value in BST

class Node {

	int data;
	Node left, right;

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

class BinaryTree {

	Node root;

	// Function to find ceil of a given input in BST.
	// If input is more than the max key in BST,
	// return -1
	int Ceil(Node node, int input)
	{

		// Base case
		if (node == null) {
			return -1;
		}

		// We found equal key
		if (node.data == input) {
			return node.data;
		}

		// If root's key is smaller,
		// ceil must be in right subtree
		if (node.data < input) {
			return Ceil(node.right, input);
		}

		// Else, either left subtree or root
		// has the ceil value
		int ceil = Ceil(node.left, input);

		return (ceil >= input) ? ceil : node.data;
	}

	// Driver Code
	public static void main(String[] args)
	{
		BinaryTree tree = new BinaryTree();
		tree.root = new Node(8);
		tree.root.left = new Node(4);
		tree.root.right = new Node(12);
		tree.root.left.left = new Node(2);
		tree.root.left.right = new Node(6);
		tree.root.right.left = new Node(10);
		tree.root.right.right = new Node(14);
		for (int i = 0; i < 16; i++) {

			System.out.println(i + " " + tree.Ceil(tree.root, i));
		}
	}
}

// This code has been done by Pranjal rajput