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
Implementation:
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 print nodes 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] # print when 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 |
Javascript
<script> // Javascript 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 */ class Node { constructor(data) { this.left = null; this.right = null; this.data = data; } } // Function to add a new node function newNode(data) { let newnode = new Node(data); return newnode; } // Function to print nodes of given level function printKDistant(root, klevel) { let q = []; let level = 1; let flag = false; q.push(root); // extra null is added to keep track // of all the nodes to be added before // level is incremented by 1 q.push(null); while (q.length > 0) { let temp = q[0]; // print when level is equal to k if (level == klevel && temp != null) { flag = true; document.write( temp.data + " "); } q.shift(); if (temp == null) { if (q[0] != null) q.push(null); level += 1; // break the loop if level exceeds // the given level number if (level > klevel) break; } else { if (temp.left != null) q.push(temp.left); if (temp.right != null) q.push(temp.right); } } document.write("</br>"); return flag; } // create a binary tree let 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); document.write( "data at level 1 : "); let ret = printKDistant(root, 1); if (ret == false) document.write( "Number exceeds total " + "number of levels" + "</br>"); document.write("data at level 2 : "); ret = printKDistant(root, 2); if (ret == false) document.write("Number exceeds total " + "number of levels" + "</br>"); document.write( "data at level 3 : "); ret = printKDistant(root, 3); if (ret == false) document.write("Number exceeds total " + "number of levels" + "</br>"); document.write( "data at level 6 : "); ret = printKDistant(root, 6); if (ret == false) document.write( "Number exceeds total" + "number of levels" + "</br>"); // This code is contributed by suresh07. </script> |
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
Time Complexity: O(n) where n = Number of nodes
Space Complexity: O(n)
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