Floor and Ceil from a BST | Program to find ceil of a given value in BST ; A binary tree node has key , left child and right child ; Helper function that allocates a new node with the given key and NULL left and right pointers . ; Function to find ceil of a given input in BST . If input is more than the max key in BST , return - 1 ; Base case ; We found equal key ; If root 's key is smaller, ceil must be in right subtree ; Else , either left subtree or root has the ceil value ; Driver program to test above function
#include <bits/stdc++.h> NEW_LINE using namespace std ; class node { public : int key ; node * left ; node * right ; } ; node * newNode ( int key ) { node * Node = new node ( ) ; Node -> key = key ; Node -> left = NULL ; Node -> right = NULL ; return ( Node ) ; } int Ceil ( node * root , int input ) { if ( root == NULL ) return -1 ; if ( root -> key == input ) return root -> key ; if ( root -> key < input ) return Ceil ( root -> right , input ) ; int ceil = Ceil ( root -> left , input ) ; return ( ceil >= input ) ? ceil : root -> key ; } int main ( ) { node * root = newNode ( 8 ) ; root -> left = newNode ( 4 ) ; root -> right = newNode ( 12 ) ; root -> left -> left = newNode ( 2 ) ; root -> left -> right = newNode ( 6 ) ; root -> right -> left = newNode ( 10 ) ; root -> right -> right = newNode ( 14 ) ; for ( int i = 0 ; i < 16 ; i ++ ) cout << i << " ▁ " << Ceil ( root , i ) << endl ; return 0 ; }