# Hash Tables with Quadratic Probing Multiple Choice Questions and Answers (MCQs)

This set of Data Structures & Algorithms Multiple Choice Questions & Answers (MCQs) focuses on “Hash Tables with Quadratic Probing”.

1. Which of the following schemes does quadratic probing come under?
a) rehashing
b) extended hashing
c) separate chaining

Explanation: Quadratic probing comes under open addressing scheme to resolve collisions in hash tables.

2. Quadratic probing overcomes primary collision.
a) True
b) False

Explanation: Quadratic probing can overcome primary collision that occurs in linear probing but a secondary collision occurs in quadratic probing.

3. What kind of deletion is implemented by hashing using open addressing?
a) active deletion
b) standard deletion
c) lazy deletion
d) no deletion

Explanation: Standard deletion cannot be performed in an open addressing hash table, because the cells might have caused collision. Hence, the hash tables implement lazy deletion.

4. In quadratic probing, if the table size is prime, a new element cannot be inserted if the table is half full.
a) True
b) False

Explanation: In quadratic probing, if the table size is prime, we can insert a new element even though table is exactly half filled. We can’t insert element if table size is more than half filled.

5. Which of the following is the correct function definition for quadratic probing?
a) F(i)=i2
b) F(i)=i
c) F(i)=i+1
d) F(i)=i2+1

Explanation: The function of quadratic probing is defined as F(i)=i2. The function of linear probing is defined as F(i)=i.

6. How many constraints are to be met to successfully implement quadratic probing?
a) 1
b) 2
c) 3
d) 4

Explanation: 2 requirements are to be met with respect to table size. The table size should be a prime number and the table size should not be more than half full.

7. Which among the following is the best technique to handle collision?
b) Linear probing
c) Double hashing
d) Separate chaining

Explanation: Quadratic probing handles primary collision occurring in the linear probing method. Although secondary collision occurs in quadratic probing, it can be removed by extra multiplications and divisions.

8. Which of the following techniques offer better cache performance?
b) Linear probing
c) Double hashing
d) Rehashing

Explanation: Linear probing offers better cache performance than quadratic probing and also it preserves locality of reference.

9. What is the formula used in quadratic probing?
a) Hash key = key mod table size
b) Hash key=(hash(x)+F(i)) mod table size
c) Hash key=(hash(x)+F(i2)) mod table size
d) H(x) = x mod 17

Explanation: Hash key=(hash(x)+F(i2)) mod table size is the formula for quadratic probing. Hash key = (hash(x)+F(i)) mod table size is the formula for linear probing.

10. For the given hash table, in what location will the element 58 be hashed using quadratic probing?

 0 49 1 2 3 4 5 6 7 8 18 9 89

a) 1
b) 2
c) 7
d) 6

Explanation: Initially, 58 collides at position 8. Another collision occurs one cell away. Hence, F(i2)=4. Using quadratic probing formula, the location is obtained as 2.

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