Hash Functions: Master the Art of Efficient Data Retrieval

Question 1

Which technique is NOT used for collision resolution in hash tables?

Accepted Answer

Sorting

Answer

Chaining

Answer

Linear probing

Answer

Double hashing

Question 2

Consider a hash table with chaining collision resolution. Which data structure is typically used for chaining?

Accepted Answer

Linked list

Answer

Array

Answer

Stack

Answer

Queue

Question 3

What is the primary purpose of using a salt in the context of hash functions?

Accepted Answer

To make it computationally harder to reverse the hash

Answer

To increase the collision rate

Answer

To reduce the load factor

Answer

To improve the performance of hash lookups

Question 4

Which of the following is NOT a consideration when designing a hash function?

Accepted Answer

Reversibility

Answer

Collision avoidance

Answer

Uniform output distribution

Answer

Computational efficiency

Question 5

Which of the following is NOT an essential property of a hash function?

Accepted Answer

Collision resistance

Answer

Deterministic

Answer

Efficient

Answer

Uniform distribution

Question 6

The most prevalent collision resolution technique is:

Accepted Answer

Linear probing

Answer

Quadratic probing

Answer

Double hashing

Answer

Binary search tree

Question 7

What is the purpose of employing a load factor in a hash table?

Accepted Answer

To determine when resizing the table is necessary

Answer

To calculate the average number of collisions

Answer

To improve search performance

Answer

To reduce memory usage

Question 8

Which hash function is best suited for strings?

Accepted Answer

MurmurHash

Answer

MD5

Answer

SHA-256

Answer

CRC32

Question 9

What is the key distinction between open addressing and closed addressing hash tables?

Accepted Answer

Open addressing allows for collisions within the table, while closed addressing does not

Answer

Closed addressing allows for collisions within the table, while open addressing does not

Answer

Open addressing uses chaining to resolve collisions, while closed addressing uses probing

Answer

Closed addressing uses chaining to resolve collisions, while open addressing uses probing

Question 10

What is the primary objective of a perfect hash function?

Accepted Answer

To completely eliminate all collisions

Answer

To minimize the number of collisions

Answer

To ensure identical hash values for all keys

Answer

To reduce search time complexity to O(1)

Question 11

Which of the following is NOT a characteristic of an ideal hash function?

Accepted Answer

Irreversibility

Answer

Uniform distribution of hash values

Answer

Minimization of collisions

Answer

Deterministic output for a given input

Question 12

What is the primary purpose of a collision resolution technique?

Accepted Answer

To detect and handle collisions in a hash table

Answer

To enhance the performance of hash table lookups

Answer

To ensure that all keys are mapped to distinct hash values

Answer

To prevent the occurrence of hash collisions

Question 13

What does the load factor of a hash table represent?

Accepted Answer

The ratio of the number of keys in the table to its size

Answer

The number of collisions that have occurred in the table

Answer

The average number of keys stored in each bucket of the table

Answer

The maximum number of keys that the table can hold

Question 14

What is the primary function of a Bloom filter?

Accepted Answer

To efficiently determine whether an element is present in a set

Answer

To store a large number of keys in a space-efficient manner

Answer

To resolve collisions in a hash table

Answer

To generate hash values for input keys

Question 15

What is a key advantage of using a cryptographic hash function?

Accepted Answer

Resistance to collision attacks

Answer

Fast computation

Answer

Low memory usage

Answer

Simple implementation

Question 16

What is the time complexity of searching for an element in a hash table with n keys using linear probing?

Accepted Answer

O(n)

Answer

O(1)

Answer

O(log n)

Answer

O(n^2)

Question 17

Which of the following are essential properties of an effective hash function?

Accepted Answer

Deterministic, efficient, and collision-resistant

Answer

Deterministic and efficient

Answer

Collision-free and efficient

Answer

Collision-resistant, fast, and scalable

Question 18

What is the primary objective of employing a collision resolution technique in a hash table?

Accepted Answer

To handle existing collisions in an efficient manner

Answer

To minimize the likelihood of collisions

Answer

To improve the performance of the hash function

Answer

To prevent data corruption

Question 19

Which of the following is not a commonly used collision resolution technique?

Accepted Answer

Binary search tree

Answer

Linear probing

Answer

Quadratic probing

Answer

Chaining

Question 20

What is the purpose of a load factor in the context of a hash table?

Accepted Answer

To assess the level of fullness within the hash table

Answer

To determine the ideal size of the hash table

Answer

To regulate the number of collisions that occur

Answer

To enhance the efficiency of the hash function

Question 21

Which of the following is a crucial characteristic of an effective hash function?

Accepted Answer

Deterministic and computationally efficient

Answer

Non-deterministic and computationally efficient

Answer

Random and computationally efficient

Answer

Random and computationally expensive

Question 22

What is the purpose of employing a collision resolution strategy in a hash table?

Accepted Answer

To effectively handle situations where multiple keys share the same hash index

Answer

To enhance the efficiency of hash table insertion operations

Answer

To minimize the size of the hash table

Question 23

Which collision resolution technique involves organizing hashed elements into linked lists?

Accepted Answer

Chaining

Answer

Quadratic probing

Answer

Linear probing

Answer

Double hashing

Question 24

What is the purpose of applying the modulus operation while computing hash values?

Accepted Answer

To map a large range of input values into the limited size of the hash table

Answer

To generate random hash values

Answer

To minimize the number of collisions

Question 25

Which of the following hash functions is designed to resist collision attacks?

Accepted Answer

SHA-256

Answer

MD5

Answer

XOR

Answer

CRC32

Question 26

What is the primary advantage of using a hash table in comparison to a binary search tree?

Accepted Answer

Improved average search and insertion performance

Answer

Ordered data storage

Answer

Ability to handle duplicate elements

Answer

Lower memory requirements

Question 27

What is the purpose of a Bloom filter?

Accepted Answer

A space-efficient data structure for approximate set membership testing

Answer

A collision resolution technique for hash tables

Answer

A hash table that supports duplicate elements

Question 28

Which property of a hash function ensures that it maps distinct inputs to distinct outputs?

Accepted Answer

Injectivity

Answer

Bijectivity

Answer

Surjectivity

Answer

Idempotency

Question 29

In a hash table, what is the primary role of a hash function?

Accepted Answer

To map keys to memory locations efficiently

Answer

To optimize memory utilization

Answer

To improve search and retrieval performance

Answer

To guarantee the uniqueness of keys

Question 30

When designing a hash function, what is a crucial issue to consider?

Accepted Answer

Minimizing hash collisions

Answer

Ensuring hash underloading

Answer

Avoiding hash conflicts

Answer

Preventing hash overloading

Question 31

Which of the following is a type of cryptographic hash function?

Accepted Answer

SHA-256

Answer

Linear probing

Answer

Chaining

Answer

Double hashing

Question 32

In a hash table, how does the load factor impact performance?

Accepted Answer

A higher load factor increases the probability of collisions

Answer

A lower load factor enhances search efficiency

Answer

The load factor has no effect on performance

Question 33

What is the purpose of adding a salt to a hash function?

Accepted Answer

To thwart rainbow table attacks

Answer

To increase the collision rate

Answer

To ensure hash uniqueness

Answer

To improve hash distribution

Question 34

Which of the following is a crucial property of a hash function?

Accepted Answer

Deterministic

Answer

Random

Answer

Injective

Answer

Unique

Question 35

A collision in a hash table occurs when:

Accepted Answer

Multiple keys map to the same hash value

Answer

The load factor exceeds 1

Answer

The hash table is full

Answer

A key cannot be located in the hash table

Question 36

The primary objective of using a hash function is to:

Accepted Answer

Effectively distribute keys across a hash table

Answer

Generate unique identifiers

Answer

Compress files

Answer

Encrypt data

Question 37

What does the load factor of a hash table represent?

Accepted Answer

Ratio of the number of keys to the size of the hash table

Answer

Number of collisions divided by the size of the hash table

Answer

Average number of keys per slot

Question 38

What is the worst-case time complexity for searching a key in a perfectly balanced binary search tree?

Accepted Answer

O(log n)

Answer

O(log n^2)

Answer

O(n)

Answer

O(n^2)

Question 39

Which advantage is offered by a binary search tree over a hash table?

Accepted Answer

Ordered traversal

Answer

Faster search time

Answer

Simpler implementation

Answer

Lower memory usage

Question 40

What is the primary limitation of using hash functions?

Accepted Answer

Potential for collisions

Answer

High time complexity

Answer

Memory inefficiency

Answer

Difficult to implement

Question 41

A hash function that maps two different inputs to the same hash value is exhibiting:

Accepted Answer

Collision

Answer

Injection

Answer

Surjection

Answer

Bijection

Question 42

Which collision resolution technique involves creating a linked list at each hash table slot to store colliding elements?

Accepted Answer

Separate Chaining

Answer

Open Addressing

Answer

Double Hashing

Answer

Linear Probing

Question 43

In open addressing, what happens when a new element hashes to a slot that is already occupied?

Accepted Answer

The algorithm searches for the next available slot using a predefined probing strategy.

Answer

The hash function is recalculated.

Answer

The element is discarded.

Answer

A separate chain is created.

Question 44

What is a potential disadvantage of using separate chaining for collision resolution?

Accepted Answer

It can lead to increased search time in the worst case due to potential long linked lists.

Answer

It is more complex to implement than open addressing.

Answer

It requires a larger hash table.

Question 45

How does a hash function contribute to efficient searching in a hash table?

Accepted Answer

It provides a direct mapping to the location of an element, reducing search time compared to exhaustive or linear searches.

Answer

It guarantees that all elements will be evenly distributed.

Answer

It eliminates the need for collision resolution.

Question 46

Which of the following is an example of a common cryptographic hash function?

Accepted Answer

SHA-256

Answer

Division Method

Answer

Separate Chaining

Answer

Linear Probing

Question 47

In a hash table using open addressing, what is the load factor?

Accepted Answer

The ratio of the number of elements to the size of the hash table.

Answer

The maximum number of probes needed to find an element.

Answer

The average number of collisions per element.

Question 48

You are designing a hash table to store a large dataset of student records. Which collision resolution technique would likely be most suitable for this scenario?

Accepted Answer

Separate Chaining

Answer

Quadratic Probing

Answer

Linear Probing

Question 49

What is the primary purpose of a hash function in the context of a hash table?

Accepted Answer

To efficiently map keys to their corresponding values, allowing for fast retrieval.

Answer

To encrypt sensitive data before storing it in a database.

Answer

To generate random numbers for use in statistical simulations.

Question 50

Which characteristic is undesirable in a good hash function?

Accepted Answer

Predictable output for similar inputs, leading to potential vulnerabilities.

Answer

Low computational complexity, enabling efficient execution.

Answer

Uniform distribution of hash values, ensuring fair distribution.

Answer

Minimized collisions for different keys, enhancing performance.

Question 51

What occurs in a collision within a hash table, and how does it impact efficiency?

Accepted Answer

A collision happens when two different keys hash to the same index, resulting in slower search and insertion times due to the need for additional comparisons.

Answer

A collision occurs when the hash table becomes full, preventing further insertions.

Question 52

Which collision resolution strategy involves searching for the next available slot in the hash table by sequentially probing from the initial hashed index?

Accepted Answer

Linear Probing

Answer

Double Hashing

Answer

Separate Chaining

Answer

Cuckoo Hashing

Question 53

How does separate chaining handle collisions in a hash table?

Accepted Answer

It stores colliding elements in a linked list at the shared index, allowing for efficient retrieval even in case of collisions.

Answer

It uses a secondary hash function to find an alternative index, minimizing the likelihood of collisions.

Answer

It resizes the hash table and rehashes all existing elements, eliminating the possibility of collisions.

Question 54

What is a potential drawback of using linear probing for collision resolution in a hash table with a high load factor?

Accepted Answer

Linear probing can lead to clustering, where multiple colliding elements are stored consecutively, decreasing performance due to increased search times.

Answer

Linear probing requires the use of a secondary hash function, adding complexity to the implementation.

Answer

Linear probing increases the complexity of the hash function itself, making it less efficient.

Answer

Linear probing is not an effective method for resolving collisions, often resulting in poor performance.

Question 55

Which of the following is a cryptographic hash function widely used for security purposes?

Accepted Answer

SHA-256

Answer

MurmurHash

Answer

CityHash

Question 56

What is the role of a hash function in a blockchain data structure?

Accepted Answer

To create a unique and tamper-proof fingerprint of a block of transactions, ensuring data integrity and preventing unauthorized alterations.

Answer

To generate random numbers used in the mining process.

Answer

To encrypt the transactions within a block, securing them from unauthorized access.

Question 57

What is a common technique to mitigate the risk of collisions when using hash functions for security purposes?

Accepted Answer

Salting

Answer

Folding

Answer

Truncating

Answer

Shifting

Question 58

How does the choice of a hash function impact the overall performance of a hash table?

Accepted Answer

A well-chosen hash function can effectively distribute keys, minimizing collisions, reducing search times, and improving the efficiency of the hash table.

Answer

The hash function has no impact on performance; it only affects the security of the data.