Replace node with depth in a binary tree

Given a binary tree, replace each node with its depth value. For example, consider the following tree. Root is at depth 0, change its value to 0 and next level nodes are at depth 1 and so on.


       3                       0
      /  \                    /   \
     2    5      == >;         1     1
   /   \                   /   \
  1     4                 2     2

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

The idea is to traverse tree starting from root. While traversing pass depth of node as parameter. We can track depth by passing it as 0 for root and one-plus-current-depth for children.

Below is the implementation of the idea.

C++

// CPP program to replace every key value  
// with its depth. 
#include<bits/stdc++.h> 
using namespace std; 
  
/* A tree node structure */
struct Node 
{ 
    int data; 
    struct Node *left, *right; 
}; 
  
/* Utility function to create a 
   new Binary Tree node */
struct Node* newNode(int data) 
{ 
    Node *temp = new Node; 
    temp->data = data; 
    temp->left = temp->right = NULL;     
    return temp; 
} 
  
// Helper function replaces the data with depth 
// Note : Default value of level is 0 for root. 
void replaceNode(struct Node *node, int level=0) 
{ 
    // Base Case 
    if (node == NULL) 
        return; 
  
    // Replace data with current depth 
    node->data = level; 
  
    replaceNode(node->left, level+1); 
    replaceNode(node->right, level+1); 
} 
  
// A utility function to print inorder 
// traversal of a Binary Tree 
void printInorder(struct Node* node) 
{ 
     if (node == NULL) 
          return; 
     printInorder(node->left); 
     cout << node->data <<" "; 
     printInorder(node->right); 
} 
  
/* Driver function to test above functions */
int main() 
{ 
    struct Node *root = new struct Node; 
  
    /* Constructing tree given in 
       the above figure */
    root = newNode(3); 
    root->left = newNode(2); 
    root->right = newNode(5); 
    root->left->left = newNode(1); 
    root->left->right = newNode(4); 
      
    cout << "Before Replacing Nodes\n";     
    printInorder(root); 
    replaceNode(root);   
    cout << endl; 
      
    cout << "After Replacing Nodes\n"; 
    printInorder(root); 
      
    return 0; 
} 

Java

// Java program to replace every key value  
// with its depth.  
class GfG {  
  
/* A tree node structure */
static class Node  
{  
    int data;  
    Node left, right;  
} 
  
/* Utility function to create a  
new Binary Tree node */
static Node newNode(int data)  
{  
    Node temp = new Node();  
    temp.data = data;  
    temp.left = null; 
    temp.right = null;      
    return temp;  
}  
  
// Helper function replaces the data with depth  
// Note : Default value of level is 0 for root.  
static void replaceNode(Node node, int level)  
{  
    // Base Case  
    if (node == null)  
        return;  
  
    // Replace data with current depth  
    node.data = level;  
  
    replaceNode(node.left, level+1);  
    replaceNode(node.right, level+1);  
}  
  
// A utility function to print inorder  
// traversal of a Binary Tree  
static void printInorder(Node node)  
{  
    if (node == null)  
        return;  
    printInorder(node.left);  
    System.out.print(node.data + " ");  
    printInorder(node.right);  
}  
  
/* Driver function to test above functions */
public static void main(String[] args)  
{  
    Node root = new Node();  
  
    /* Constructing tree given in  
    the above figure */
    root = newNode(3);  
    root.left = newNode(2);  
    root.right = newNode(5);  
    root.left.left = newNode(1);  
    root.left.right = newNode(4);  
      
    System.out.println("Before Replacing Nodes");      
    printInorder(root);  
    replaceNode(root, 0);  
    System.out.println(); 
      
    System.out.println("After Replacing Nodes");  
    printInorder(root);  
      
} 
}  

Python3

# Python3 program to replace every key  
# value with its depth.  
  
class newNode: 
    def __init__(self, data): 
        self.data = data  
        self.left = self.right = None
  
# Helper function replaces the data with depth  
# Note : Default value of level is 0 for root.  
def replaceNode(node, level = 0): 
      
    # Base Case  
    if (node == None): 
        return
  
    # Replace data with current depth  
    node.data = level  
  
    replaceNode(node.left, level + 1)  
    replaceNode(node.right, level + 1) 
  
# A utility function to prinorder  
# traversal of a Binary Tree  
def printInorder(node): 
    if (node == None):  
        return
    printInorder(node.left)  
    print(node.data, end = " ") 
    printInorder(node.right) 
  
# Driver Code 
if __name__ == '__main__': 
  
    # Constructing tree given in  
    # the above figure  
    root = newNode(3)  
    root.left = newNode(2)  
    root.right = newNode(5)  
    root.left.left = newNode(1)  
    root.left.right = newNode(4)  
      
    print("Before Replacing Nodes")      
    printInorder(root)  
    replaceNode(root)  
      
    print() 
    print("After Replacing Nodes")  
    printInorder(root) 
  
# This code is contributed by PranchalK 

C#

// C# program to replace every key value  
// with its depth.  
using System; 
  
public class GfG  
{  
  
    /* A tree node structure */
    public class Node  
    {  
        public int data;  
        public Node left, right;  
    } 
  
    /* Utility function to create a  
    new Binary Tree node */
    static Node newNode(int data)  
    {  
        Node temp = new Node();  
        temp.data = data;  
        temp.left = null; 
        temp.right = null;      
        return temp;  
    }  
  
    // Helper function replaces the data with depth  
    // Note : Default value of level is 0 for root.  
    static void replaceNode(Node node, int level)  
    {  
        // Base Case  
        if (node == null)  
            return;  
  
        // Replace data with current depth  
        node.data = level;  
  
        replaceNode(node.left, level + 1);  
        replaceNode(node.right, level + 1);  
    }  
  
    // A utility function to print inorder  
    // traversal of a Binary Tree  
    static void printInorder(Node node)  
    {  
        if (node == null)  
            return;  
        printInorder(node.left);  
        Console.Write(node.data + " ");  
        printInorder(node.right);  
    }  
  
    /* Driver code*/
    public static void Main(String[] args)  
    {  
        Node root = new Node();  
  
        /* Constructing tree given in  
        the above figure */
        root = newNode(3);  
        root.left = newNode(2);  
        root.right = newNode(5);  
        root.left.left = newNode(1);  
        root.left.right = newNode(4);  
  
        Console.WriteLine("Before Replacing Nodes");      
        printInorder(root);  
        replaceNode(root, 0);  
        Console.WriteLine(); 
  
        Console.WriteLine("After Replacing Nodes");  
        printInorder(root);  
    } 
} 
  
// This code is contributed Rajput-Ji  

Output:

Before Replacing Nodes
1 2 4 3 5 

After Replacing Nodes
2 1 2 0 1

This article is contributed by Chhavi. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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My Personal Notes

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

C++

Java

Python3

C#

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