Top MCQs on Binary Search Tree (BST) Data Structure with Answers

Question 1

What is the worst case time complexity for search, insert and delete operations in a general Binary Search Tree for a skewed tree ?

• O(n) for all

• O(Logn) for all

• O(Logn) for search and insert, and O(n) for delete

• O(Logn) for search, and O(n) for insert and delete

Question 2

In delete operation of BST, we need inorder successor (or predecessor) of a node when the node to be deleted has both left and right child as non-empty. Which of the following is true about inorder successor needed in delete operation?

• Inorder Successor is always a leaf node

• Inorder successor is always either a leaf node or a node with empty left child

• Inorder successor may be an ancestor of the node

• Inorder successor is always either a leaf node or a node with empty right child

Question 3

We are given a set of n distinct elements and an unlabelled binary tree with n nodes. In how many ways can we populate the tree with the given set so that it becomes a binary search tree? (GATE CS 2011)

• 0

• 1

• n!

• (1/(n+1)).2nCn

Question 4

How many distinct binary search trees can be created out of 4 distinct keys?

• 4

• 14

• 24

• 42

Question 5

Which of the following traversal outputs the data in sorted order in a BST?

• Preorder

• Inorder

• Postorder

• Level order

Question 6

The following numbers are inserted into an empty binary search tree in the given order: 10, 1, 3, 5, 15, 12, 16. What is the height of the binary search tree (the height is the maximum distance of a leaf node from the root)? (GATE CS 2004)

• 2
  

• 3
  

• 4
  

• 6
  

Question 7

The preorder traversal sequence of a binary search tree is 30, 20, 10, 15, 25, 23, 39, 35, 42. Which one of the following is the postorder traversal sequence of the same tree?

• 10, 20, 15, 23, 25, 35, 42, 39, 30

• 15, 10, 25, 23, 20, 42, 35, 39, 30

• 15, 20, 10, 23, 25, 42, 35, 39, 30

• 15, 10, 23, 25, 20, 35, 42, 39, 30

Question 8

Consider the following Binary Search Tree

[caption width="800"] [/caption]

If we randomly search one of the keys present in above BST, what would be the expected number of comparisons?

• 2.75

• 2.25

• 2.57

• 3.25

Question 9

Which of the following traversals is sufficient to construct BST from given traversals 1) Inorder 2) Preorder 3) Postorder

• Any one of the given three traversals is sufficient
• Either 2 or 3 is sufficient
• 2 and 3
• 1 and 3

Question 10

Consider the following code snippet in C. The function print() receives root of a Binary Search Tree (BST) and a positive integer k as arguments.

C

// A BST node
struct node {
    int data;
    struct node *left, *right;
};

int count = 0;

void print(struct node *root, int k)
{
    if (root != NULL && count <= k)
    {
        print(root->right, k);
        count++;
        if (count == k)
          printf(\"%d \", root->data);
       print(root->left, k);
    }
}

What is the output of print(root, 3) where root represent root of the following BST.

                   15
                /     \\
              10      20
             / \\     /  \\
            8  12   16  25   

• 10
• 16
• 20
• 20 10