# Double Hashing Multiple choice Questions and Answers (MCQs)

## Double Hashing Multiple choice Questions and Answers (MCQs)

 Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Double hashing is one of the best methods available for open addressing.
 A True B False
Question 1 Explanation:
Double hashing is one of the best methods for open addressing because the permutations produced have many characteristics of randomly chosen permutations.

 Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the hash function used in Double Hashing?
 A (h1(k) - i*h2(k))mod m B h1(k) + h2(k) C (h1(k) + i*h2(k))mod m D (h1(k) + h2(k))mod m
Question 2 Explanation:
Double hashing uses a hash function of the form (h1(k) + i*h2(k))mod m where h1 and h2 are auxiliary hash functions and m is the size of the hash table.

 Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
On what value does the probe sequence depend on?
 A c1 B k C c2 D m
Question 3 Explanation:
The probe sequence depends in upon the key k since the initial probe position, the offset or both may vary.

 Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The value of h2(k) can be composite relatively to the hash table size m.
 A True B False
Question 4 Explanation:
The value h2(k) must be relatively prime to the hash table size m for the entire hash table to be searched. It can be ensured by having m in powers of 2 and designing h2 so that it produces an odd number.

 Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What are the values of h1(k) and h2(k) in the hash function?
 A `h1(k) = m mod k h2(k) = 1+ (m' mod k)` B `h1(k) = 1 + (m mod k) h2(k) = m' mod k` C `h1(k) = 1+ (k mod m) h2(k) = k mod m` D `h1(k) = k mod m h2(k) = 1+ (k mod m')`
Question 5 Explanation:
The values h1(k) and h2(k) are k mod m and 1+(k mod m') respectively where m is a prime number and m' is chosen slightly less than m. (m'=m-1).

There are 5 questions to complete.