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Find the node with maximum value in a Binary Search Tree

Given a Binary Search Tree, the task is to find the node with the maximum value in a BST.

For the above tree, we start with 20, then we move right 22, we keep on moving to right until we see NULL. Since right of 22 is NULL, 22 is the node with maximum value.

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: This is quite simple. Just traverse the node from root to right recursively until right is NULL. The node whose right is NULL is the node with maximum value.

C++

#include <bits/stdc++.h> 
using namespace std; 
  
/* A binary tree node has data, pointer to left child   
   and a pointer to right child */
struct node { 
    int data; 
    struct node* left; 
    struct node* right; 
}; 
  
// Function to create a new node 
struct node* newNode(int data) 
{ 
    struct node* node = (struct node*) 
        malloc(sizeof(struct node)); 
    node->data = data; 
    node->left = NULL; 
    node->right = NULL; 
  
    return (node); 
} 
  
// Function to insert a new node in BST 
struct node* insert(struct node* node, int data) 
{ 
    /* 1. If the tree is empty, return a new,       
      single node */
    if (node == NULL) 
        return (newNode(data)); 
    else { 
        /* 2. Otherwise, recur down the tree */
        if (data <= node->data) 
            node->left = insert(node->left, data); 
        else
            node->right = insert(node->right, data); 
  
        /* return the (unchanged) node pointer */
        return node; 
    } 
} 
  
// Function to find the node with maximum value 
// i.e. rightmost leaf node 
int maxValue(struct node* node) 
{    
    /* loop down to find the rightmost leaf */
    struct node* current = node; 
    while (current->right != NULL)  
        current = current->right; 
      
    return (current->data); 
} 
  
// Driver code 
int main() 
{ 
    struct node* root = NULL; 
    root = insert(root, 4); 
    insert(root, 2); 
    insert(root, 1); 
    insert(root, 3); 
    insert(root, 6); 
    insert(root, 5); 
  
    cout << "Maximum value in BST is " << maxValue(root); 
  
    return 0; 
} 

Java

// Java implementation to find the sum of last 
// 'n' nodes of the Linked List 
import java.util.*; 
  
class GFG 
{ 
  
  
/* A binary tree node has data, pointer to left child  
and a pointer to right child */
static class node 
{ 
    int data; 
    node left; 
    node right; 
}; 
  
// Function to create a new node 
static node newNode(int data) 
{ 
    node node = new node(); 
    node.data = data; 
    node.left = null; 
    node.right = null; 
  
    return (node); 
} 
  
// Function to insert a new node in BST 
static node insert(node node, int data) 
{ 
    /* 1. If the tree is empty, return a new,      
    single node */
    if (node == null) 
        return (newNode(data)); 
    else 
    { 
        /* 2. Otherwise, recur down the tree */
        if (data <= node.data) 
            node.left = insert(node.left, data); 
        else
            node.right = insert(node.right, data); 
  
        /* return the (unchanged) node pointer */
        return node; 
    } 
} 
  
// Function to find the node with maximum value 
// i.e. rightmost leaf node 
static int maxValue(node node) 
{  
    /* loop down to find the rightmost leaf */
    node current = node; 
    while (current.right != null)  
        current = current.right; 
      
    return (current.data); 
} 
  
// Driver code 
public static void main(String[] args)  
{ 
    node root = null; 
    root = insert(root, 4); 
    insert(root, 2); 
    insert(root, 1); 
    insert(root, 3); 
    insert(root, 6); 
    insert(root, 5); 
  
    System.out.println("Maximum value in BST is " + maxValue(root)); 
} 
} 
  
/* This code is contributed by PrinciRaj1992 */

Python3

import sys 
import math 
  
# A binary tree node has data, pointer to left child  
# and a pointer to right child  
class Node: 
    def __init__(self,data): 
        self.data = data 
        self.left = None
        self.right = None
  
# Function to insert a new node in BST 
def insert(root, data): 
  
    # 1. If the tree is empty, return a new,      
    # single node 
    if not root: 
        return Node(data) 
  
    # 2. Otherwise, recur down the tree 
    if data < root.data: 
        root.left = insert(root.left, data) 
    if data > root.data: 
        root.right = insert(root.right, data) 
      
    # return the (unchanged) node pointer 
    return root 
  
# Function to find the node with maximum value  
# i.e. rightmost leaf node  
def maxValue(root): 
    current = root 
      
    #loop down to find the rightmost leaf 
    while(current.right): 
        current = current.right 
    return current.data 
  
# Driver code  
if __name__=='__main__': 
    root=None
    root = insert(root,2) 
    root = insert(root,1) 
    root = insert(root,3) 
    root = insert(root,6) 
    root = insert(root,5) 
    print("Maximum value in BST is {}".format(maxValue(root))) 
  
# This code is contributed by Vikash Kumar 37 

C#

// C# implementation to find the sum of last  
// 'n' nodes of the Linked List  
using System; 
  
class GFG  
{  
  
  
/* A binary tree node has data, pointer to left child  
and a pointer to right child */
public class node  
{  
    public int data;  
    public node left;  
    public node right;  
};  
  
// Function to create a new node  
static node newNode(int data)  
{  
    node node = new node();  
    node.data = data;  
    node.left = null;  
    node.right = null;  
  
    return (node);  
}  
  
// Function to insert a new node in BST  
static node insert(node node, int data)  
{  
    /* 1. If the tree is empty, return a new,  
    single node */
    if (node == null)  
        return (newNode(data));  
    else
    {  
        /* 2. Otherwise, recur down the tree */
        if (data <= node.data)  
            node.left = insert(node.left, data);  
        else
            node.right = insert(node.right, data);  
  
        /* return the (unchanged) node pointer */
        return node;  
    }  
}  
  
// Function to find the node with maximum value  
// i.e. rightmost leaf node  
static int maxValue(node node)  
{  
    /* loop down to find the rightmost leaf */
    node current = node;  
    while (current.right != null)  
        current = current.right;  
      
    return (current.data);  
}  
  
// Driver code  
public static void Main(String[] args)  
{  
    node root = null;  
    root = insert(root, 4);  
    insert(root, 2);  
    insert(root, 1);  
    insert(root, 3);  
    insert(root, 6);  
    insert(root, 5);  
  
    Console.WriteLine("Maximum value in BST is " + maxValue(root));  
}  
}  
  
// This code is contributed by Rajput-Ji 

Output:

Maximum value in BST is 6

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Improved By : Vikash Kumar 37, princiraj1992, Rajput-Ji

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