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Validate Binary Tree Nodes

Posted: 25 Mar, 2021
Difficulty: Moderate

PROBLEM STATEMENT

Try Problem

You are given ‘N’ binary tree nodes numbered from 0 to N - 1 where node ‘i’ has two children LEFT_CHILD[i] and RIGHT_CODE[i]. Return ‘True’ if and only if all the given nodes form exactly one valid binary tree. If node ‘i’ has no left child then 'LEFT_CHILD[i]' will equal -1, similarly for the right child.

Example:

Let’s say we have n=4 nodes, 'LEFT_CHILD' = {1, -1, 3, -1} and 
RIGHT_CHILD = {2, -1, -1, -1}. So the resulting tree will look like this:

It will return True as there is only one valid binary tree and each node has only one parent and there is only one root.
Input format:
The very first line of input contains an integer ‘T’ denoting the 
number of test cases. 

The first line of every test case contains an integer ‘N’ denoting 
the number of nodes of the tree.

The next two lines of every test case contain the 'LEFT_CHILD' array and 
'RIGHT_CHILD' array respectively.
Output format:
For each test case, return either ‘Yes’ or ‘No’ that whether from given nodes, we can form exactly one valid binary tree or not. 


Output for each test case is printed on a separate line.
Note:
You do not need to print anything, it has already been taken care of. Just return ‘True’ or ‘False’ that whether from given nodes we can form exactly one valid binary tree or not. 


The nodes have no values and that we only use the node numbers in this problem.
Constraints:
1 <= T <= 10
1 <= N <= 10^4
LEFT_CHILD.length == RIGHT_CHILD.length == N
-1 <= LEFT_CHILD[i], RIGHT_CHILD[i] <= N - 1

Time Limit: 1 sec