MADE EASY TEST SERIES

Question

Consider the following C program segment where tree node represent a node in a binary tree

When the pointer to the root of a tree is passed as the argument to find something the value return by the function corresponding to the

a> Total number of nodes in the tree

b> Number of internal nodes in the tree

c> Number of leaf nodes in the tree

d> Number of levels in the tree

Comments

Please guide me. I am getting option A as answer.

Answer 1

Aswer is A. make a tree and traverse. the code is calclating number of left child , number of right child and then returning the total including itself. so 1 is added.

Comments

I am also getting same (sorry my previous comment was wrong) BUT Made easy says correct answer is B.

Answer 2

Correct answer is B : number of internal nodes,

At each time  whenever we will pass the leaf node to the function , it will return 0 because

root->left == NULL and root->right == NULL  then return 0.

So, at each internal node, 1 is added to the result of immediate child nodes which is 1 + return value of left subtree + return value of right subtree. But the leaf nodes are returning 0. So, contribution will only be from the internal nodes.

Hence, overall addition will be for all internal nodes and leaf nodes will not be counted.

Comments

Agreed that Lvalue and Rvalue will be returned as zero  but then 1 will be added and 1+0+0 will be returned to the parent node. Please correct me if I am wrong.

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1 will be added only when the current node have atleast one child otherwise zero.

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Take a tree and traverse it, you will get option A.

Answer 3

As per the code, answer should be b.

Comments

Take a tree and traverse it, you will get option A.

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but suppose if i take only a single node..  it should return 1 that means total no. of nodes present  = 1 i.e op A.

but for a single node or root where left is NULL and right is NULL and thereby returning 0.

I think 0 is not the desirable answer for option A

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Yes your observation is correct. But I am getting option B in all other cases. Please guide me.

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yes it should be option B. You just  run the code by yourself  of a binary tree having 2 level (or any level you want)

then you will observe that the root is returning  the number of  nodes that are not leaf nodes...

i.e the number of internal nodes. Hope you have understood.