Print nodes at k distance from root | Iterative
Given a root of a tree, and an integer k. Print all the nodes which are at k distance from root.
Example :
Input :
20
/ \
10 30
/ \ / \
5 15 25 40
/
12
and k = 3
Root is at level 1.
Output :
5 15 25 40
Recursive approach to this problem is discussed here
Following is the iterative approach.
The solution is similar to Getting level of node in Binary Tree
C++
// CPP program to print all nodes of level k// iterative approach /* binary treeroot is at level 1 20 / \ 10 30 / \ / \ 5 15 25 40 / 12 */#include <bits/stdc++.h>using namespace std; // Node of binary treestruct Node { int data; Node* left, * right;}; // Function to add a new nodeNode* newNode(int data){ Node* newnode = new Node(); newnode->data = data; newnode->left = newnode->right = NULL;} // Function to print nodes of given levelbool printKDistant(Node* root, int klevel){ queue<Node*> q; int level = 1; bool flag = false; q.push(root); // extra NULL is pushed to keep track // of all the nodes to be pushed before // level is incremented by 1 q.push(NULL); while (!q.empty()) { Node* temp = q.front(); // print when level is equal to k if (level == klevel && temp != NULL) { flag = true; cout << temp->data << " "; } q.pop(); if (temp == NULL) { if (q.front()) q.push(NULL); level += 1; // break the loop if level exceeds // the given level number if (level > klevel) break; } else { if (temp->left) q.push(temp->left); if (temp->right) q.push(temp->right); } } cout << endl; return flag;} // Driver codeint main(){ // create a binary tree Node* root = newNode(20); root->left = newNode(10); root->right = newNode(30); root->left->left = newNode(5); root->left->right = newNode(15); root->left->right->left = newNode(12); root->right->left = newNode(25); root->right->right = newNode(40); cout << "data at level 1 : "; int ret = printKDistant(root, 1); if (ret == false) cout << "Number exceeds total number of levels\n"; cout << "data at level 2 : "; ret = printKDistant(root, 2); if (ret == false) cout << "Number exceeds total number of levels\n"; cout << "data at level 3 : "; ret = printKDistant(root, 3); if (ret == false) cout << "Number exceeds total number of levels\n"; cout << "data at level 6 : "; ret = printKDistant(root, 6); if (ret == false) cout << "Number exceeds total number of levels\n"; return 0;} |
Java
// Java program to print all nodes of level k // iterative approach /* binary tree root is at level 1 20 / \ 10 30 / \ / \ 5 15 25 40 / 12 */ import java.util.*;class GFG{ // Node of binary tree static class Node { int data; Node left, right; } // Function to add a new node static Node newNode(int data) { Node newnode = new Node(); newnode.data = data; newnode.left = newnode.right = null; return newnode;} // Function to print nodes of given level static boolean printKDistant(Node root, int klevel) { Queue<Node> q = new LinkedList<>(); int level = 1; boolean flag = false; q.add(root); // extra null is added to keep track // of all the nodes to be added before // level is incremented by 1 q.add(null); while (q.size() > 0) { Node temp = q.peek(); // print when level is equal to k if (level == klevel && temp != null) { flag = true; System.out.print( temp.data + " "); } q.remove(); if (temp == null) { if (q.peek() != null) q.add(null); level += 1; // break the loop if level exceeds // the given level number if (level > klevel) break; } else { if (temp.left != null) q.add(temp.left); if (temp.right != null) q.add(temp.right); } } System.out.println(); return flag; } // Driver code public static void main(String srga[]){ // create a binary tree Node root = newNode(20); root.left = newNode(10); root.right = newNode(30); root.left.left = newNode(5); root.left.right = newNode(15); root.left.right.left = newNode(12); root.right.left = newNode(25); root.right.right = newNode(40); System.out.print( "data at level 1 : "); boolean ret = printKDistant(root, 1); if (ret == false) System.out.print( "Number exceeds total " + "number of levels\n"); System.out.print("data at level 2 : "); ret = printKDistant(root, 2); if (ret == false) System.out.print("Number exceeds total " + "number of levels\n"); System.out.print( "data at level 3 : "); ret = printKDistant(root, 3); if (ret == false) System.out.print("Number exceeds total " + "number of levels\n"); System.out.print( "data at level 6 : "); ret = printKDistant(root, 6); if (ret == false) System.out.print( "Number exceeds total" + "number of levels\n"); } } // This code is contributed by Arnab Kundu |
Python3
# Python3 program to print all nodes of level k # iterative approach """ binary tree root is at level 1 20 / \ 10 30 / \ / \ 5 15 25 40 / 12 """ # Node of binary tree # Function to add a new nodeclass newNode: def __init__(self, data): self.data = data self.left = self.right = None # Function to prnodes of given level def printKDistant( root, klevel): q = [] level = 1 flag = False q.append(root) # extra None is appended to keep track # of all the nodes to be appended # before level is incremented by 1 q.append(None) while (len(q)): temp = q[0] # prwhen level is equal to k if (level == klevel and temp != None): flag = True print(temp.data, end = " ") q.pop(0) if (temp == None) : if (len(q)): q.append(None) level += 1 # break the loop if level exceeds # the given level number if (level > klevel) : break else: if (temp.left) : q.append(temp.left) if (temp.right) : q.append(temp.right) print() return flag # Driver Code if __name__ == '__main__': root = newNode(20) root.left = newNode(10) root.right = newNode(30) root.left.left = newNode(5) root.left.right = newNode(15) root.left.right.left = newNode(12) root.right.left = newNode(25) root.right.right = newNode(40) print("data at level 1 : ", end = "") ret = printKDistant(root, 1) if (ret == False): print("Number exceeds total", "number of levels") print("data at level 2 : ", end = "") ret = printKDistant(root, 2) if (ret == False) : print("Number exceeds total", "number of levels") print("data at level 3 : ", end = "") ret = printKDistant(root, 3) if (ret == False) : print("Number exceeds total", "number of levels") print("data at level 6 : ", end = "") ret = printKDistant(root, 6) if (ret == False): print("Number exceeds total number of levels") # This code is contributed # by SHUBHAMSINGH10 |
C#
// C# program to print all nodes of level k // iterative approach /* binary tree root is at level 1 20 / \ 10 30 / \ / \ 5 15 25 40 / 12 */ using System;using System.Collections.Generic; class GFG { // Node of binary tree public class Node { public int data; public Node left, right; } // Function to add a new node static Node newNode(int data) { Node newnode = new Node(); newnode.data = data; newnode.left = newnode.right = null; return newnode; } // Function to print nodes of given level static Boolean printKDistant(Node root, int klevel) { Queue<Node> q = new Queue<Node>(); int level = 1; Boolean flag = false; q.Enqueue(root); // extra null is added to keep track // of all the nodes to be added before // level is incremented by 1 q.Enqueue(null); while (q.Count > 0) { Node temp = q.Peek(); // print when level is equal to k if (level == klevel && temp != null) { flag = true; Console.Write( temp.data + " "); } q.Dequeue(); if (temp == null) { if (q.Count > 0&&q.Peek() != null) q.Enqueue(null); level += 1; // break the loop if level exceeds // the given level number if (level > klevel) break; } else { if (temp.left != null) q.Enqueue(temp.left); if (temp.right != null) q.Enqueue(temp.right); } } Console.Write("\n"); return flag; } // Driver code public static void Main(String []srga) { // create a binary tree Node root = newNode(20); root.left = newNode(10); root.right = newNode(30); root.left.left = newNode(5); root.left.right = newNode(15); root.left.right.left = newNode(12); root.right.left = newNode(25); root.right.right = newNode(40); Console.Write( "data at level 1 : "); Boolean ret = printKDistant(root, 1); if (ret == false) Console.Write( "Number exceeds total " + "number of levels\n"); Console.Write("data at level 2 : "); ret = printKDistant(root, 2); if (ret == false) Console.Write("Number exceeds total " + "number of levels\n"); Console.Write( "data at level 3 : "); ret = printKDistant(root, 3); if (ret == false) Console.Write("Number exceeds total " + "number of levels\n"); Console.Write( "data at level 6 : "); ret = printKDistant(root, 6); if (ret == false) Console.Write( "Number exceeds total" + "number of levels\n"); } } // This code is contributed by Princi Singh |
Output:
data at level 1 : 20 data at level 2 : 10 30 data at level 3 : 5 15 25 40 data at level 6 : Number exceeds total number of levels
This article is contributed by Mandeep Singh. 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.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.
