New update is available. Click here to update.

Solve problems & track your progress

Checkout your overall progress in every topic here

Become

Sensei

in DSA topics

Open the topic and solve more problems associated with it to improve your skills

Check out the skill meter for every topic

See how many problems you are left with to solve for cracking any stage. Score more than zero to get your progress counted.

Problem

Submissions

Print Nodes at Distance K From a Given Node

Contributed by

Prashansa

Last Updated: 23 Feb, 2023

Hard

0/120

Avg time to solve 20 mins

Success Rate 80 %

13 upvotes

Problem Statement

You are given an arbitrary binary tree, a node of the tree, and an integer 'K'. You need to find all such nodes which have a distance K from the given node and return the list of these nodes.

Distance between two nodes in a binary tree is defined as the number of connections/edges in the path between the two nodes.

Note:

1. A binary tree is a tree in which each node has at most two children. 
2. The given tree will be non-empty.
3. The given tree can have multiple nodes with the same value.
4. If there are no nodes in the tree which are at distance = K from the given node, return an empty list.
5. You can return the list of values of valid nodes in any order. For example if the valid nodes have values 1,2,3, then you can return {1,2,3} or {3,1,2} etc.

Detailed explanation ( Input/output format, Notes, Images )

Input Format:

The first line of the input contains an integer T, denoting the number of test cases to run. 

The first line of each test case will contain the values of the nodes of the tree in the level order form ( -1 for NULL node). Refer to the example below for further explanation.

The second line of each test case contains the value of the target node.

The third and the last line of each test case contains the integer K denoting the distance at which nodes are to be found. 

Example:

Consider the binary tree:

The input for the tree depicted in the above image would be :

3
5 1
6 2 0 8
-1 -1 7 4 -1 -1 -1 -1
-1 -1 -1 -1

Explanation :
Level 1 :
The root node of the tree is 3

Level 2 :
Left child of 3 = 5
Right child of 3 = 1

Level 3 :
Left child of 5 = 6
Right child of 5 = 2
Left child of 1 = 0
Right child of 1 = 8

Level 4 :
Left child of 6 = null (-1)
Right child of 6 = null(-1)
Left child of 2 = 7
Right child of 2 = 4
Left child of 0 = null (-1)
Right child of 0 = null (-1)
Left child of 8 = null (-1)
Right child of 8 = null (-1)

Level 5 :
Left child of 7 = null (-1)
Right child of 7 = null (-1)
Left child of 4 = null (-1)
Right child of 4 = null (-1)

The first not-null node (of the previous level) is treated as the parent of the first two nodes of the current level. The second not-null node (of the previous level) is treated as the parent node for the next two nodes of the current level and so on.

The input ends when all nodes at the last level are null (-1).

Output Format :

For each test case, print the values of all nodes at distance = K, from the given target node.

Note:

You do not need to print anything, it has already been taken care of. Just implement the given function.

Constraints:

1 <= T <= 100
1 <= N <= 3000
0 <= K <= 3000
0 <= nodeValue <= 3000

Where nodeValue donates the value of the node.

Time Limit: 1 sec

Sample Input 1 :

1
3 5 1 6 2 0 8 -1 -1 7 4 -1 -1 -1 -1 -1 -1 -1 -1
5
2

Sample Output 1 :

7 4 1

Explanation For The Sample Output 1:

Target Node is 5. Nodes at distance 1 from 5 are {6, 2, 3} and nodes at distance 2 are {7, 4, 1}.

Sample Input 2:

1
1 2 3 4 5 -1 -1 6 -1 -1 -1 -1 -1
5
3

Sample Output 2:

6 3

Explanation For The Sample Output 2:

The tree will be generated as above. The target node is 5 and K = 3. The nodes at distance 1 from node 5 are {2}, nodes at distance 2 from node 5 are {1, 4} and nodes at distance 3 from node 5 are {6, 3}.

Auto

Console