Hashing: A Comprehensive Guide for Data Structures and Algorithms

Question 1

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

Accepted Answer

Completely eliminates collisions

Answer

Determines a unique index for each key

Answer

Distributes keys evenly across the hash table

Answer

Computes quickly

Question 2

Which collision resolution technique involves linking colliding elements in a list within the hash table?

Accepted Answer

Chaining

Answer

Open addressing

Answer

Perfect hashing

Answer

Double hashing

Question 3

What is the primary purpose of a bloom filter in the context of hashing?

Accepted Answer

To provide a probabilistic check for membership in a set

Answer

To reduce the likelihood of collisions

Answer

To improve the performance of hash joins

Answer

To prevent hash table overflows

Question 4

What is the key difference between a closed hash table and an open hash table?

Accepted Answer

Closed hash tables have fixed-size arrays, while open hash tables use linked lists or trees to store data.

Answer

Closed hash tables are more efficient for small datasets, while open hash tables are more efficient for large datasets.

Answer

Closed hash tables allow duplicate keys, while open hash tables do not.

Answer

There is no difference between closed and open hash tables.

Question 5

Which of the following is NOT a collision resolution technique specifically used in hashing?

Accepted Answer

Binary Search

Answer

Linear Probing

Answer

Chaining

Answer

Quadratic Probing

Question 6

In hashing, what is the primary purpose of a hash table?

Accepted Answer

Map keys to values

Answer

Sort elements in ascending order

Answer

Compare string similarity

Answer

Compress large data sets

Question 7

In hash tables, which of these is NOT a method for handling collisions?

Accepted Answer

Sorting

Answer

Chaining

Answer

Linear probing

Answer

Quadratic probing

Question 8

Which of the following is a critical characteristic of hashing? It maps a key to:

Accepted Answer

A unique location in a data structure

Answer

A hash function to generate a key

Answer

Data in a linear fashion

Answer

An object-oriented programming paradigm

Question 9

What is the primary purpose of a hash function? It:

Accepted Answer

Converts a key into a unique numerical value

Answer

Resolves collisions in a hash table

Answer

Performs search operations in a hash table

Answer

Stores data in a hash table

Question 10

In hashing, the primary data structure employed is:

Accepted Answer

Hash Table

Answer

Array

Answer

Linked List

Answer

Tree

Question 11

What is the primary drawback associated with using a hash function?

Accepted Answer

Potential for collisions

Answer

Excessive memory consumption

Answer

Slow insertion and deletion operations

Answer

Difficulty in maintaining sorted data

Question 12

In a hash table, what is the purpose of the load factor?

Accepted Answer

To indicate the fullness of the hash table

Answer

To determine the efficiency of collision resolution

Answer

To calculate the number of elements in the hash table

Answer

To optimize memory usage

Question 13

What is the primary purpose of a hash function?

Accepted Answer

To generate a unique key for each data element

Answer

To resolve collisions in a hash table

Question 14

Which collision resolution technique involves creating a linked list for colliding elements?

Accepted Answer

Chaining

Answer

Linear probing

Question 15

What is the load factor of a hash table?

Accepted Answer

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

Answer

The number of collisions that occur during insertion

Question 16

What is the benefit of using double hashing for collision resolution?

Accepted Answer

To reduce the number of collisions

Answer

To increase the search efficiency

Question 17

What is the key distinction between a hash table and a binary search tree?

Accepted Answer

Hash tables use hashing, while binary search trees use sorting.

Answer

Binary search trees allow duplicate elements, while hash tables do not.

Question 18

In a hash table, what does the load factor measure?

Accepted Answer

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

Answer

The number of collisions that have occurred.

Answer

The average number of probes required to find an element.

Answer

The worst-case time complexity of the hash table.

Question 19

In hash tables, what is the fundamental difference between open and closed addressing?

Accepted Answer

Open addressing allows collisions to be handled by storing elements in overflow areas, while closed addressing does not.

Answer

Closed addressing allows collisions to be handled by storing elements in overflow areas, while open addressing does not.

Answer

Open addressing is more efficient than closed addressing.

Answer

Closed addressing is more efficient than open addressing.

Question 20

Which of the following hash functions employs bit manipulation techniques?

Accepted Answer

Mid-square method

Answer

Division method

Answer

Multiplication method

Answer

Radix method

Question 21

What is the primary purpose of a bloom filter?

Accepted Answer

Efficient membership testing in large datasets.

Answer

Storing key-value pairs in a hash table.

Answer

Preventing collisions in a hash table.

Answer

Enhancing the worst-case performance of a hash table.

Question 22

How does Locality-Sensitive Hashing (LSH) enable efficient near neighbor search in high-dimensional data?

Accepted Answer

LSH projects high-dimensional data into a lower-dimensional space while maintaining similarities.

Answer

LSH uses multiple hash tables with different hash functions to reduce collisions.

Answer

LSH employs a unique collision resolution method that guarantees finding the closest neighbor.

Answer

LSH eliminates the need for a distance metric in near neighbor search.

Question 23

What is the primary purpose of a collision resolution technique in hashing?

Accepted Answer

To manage scenarios where various keys share the same hash index.

Answer

To enhance the efficiency of hash table operations.

Answer

To safeguard data integrity.

Answer

To ensure an even distribution of elements within the hash table.

Question 24

Which option is NOT a commonly used collision resolution technique in hashing?

Accepted Answer

Sorting the hash table

Answer

Open addressing

Answer

Chaining

Answer

Linear probing

Question 25

Compared to a linked list, what advantage does a hash table provide?

Accepted Answer

Faster search and retrieval operations.

Answer

Reduced memory consumption.

Answer

Improved handling of duplicate keys.

Answer

Simplified implementation.

Question 26

What is the primary reason for rehashing in a hash table implementation?

Accepted Answer

To expand the hash table's size when the load factor exceeds a certain threshold.

Answer

To reduce the hash table's size when the load factor falls below a certain threshold.

Answer

To redistribute elements within the hash table for better performance.

Answer

To remove duplicate keys from the hash table.

Question 27

In hashing, which technique is NOT used for collision resolution?

Accepted Answer

Sorting

Answer

Linear Probing

Answer

Chaining

Answer

Double Hashing

Question 28

Which method is NOT typically used to handle collisions in a hash table?

Accepted Answer

Binary Search Tree

Answer

Linear Probing

Answer

Chaining

Answer

Quadratic Probing

Question 29

How does a well-designed hash function contribute to minimizing collisions and enhancing the efficiency of a hash table?

Accepted Answer

It distributes data evenly across the hash table, reducing the likelihood of multiple keys mapping to the same hash value.

Answer

It eliminates duplicate keys in the hash table.

Answer

It increases the size of the hash table.

Answer

It uses a random number generator to generate hash values.

Question 30

How does consistent hashing improve data distribution compared to traditional hashing?

Accepted Answer

Distributes data evenly across servers, reducing overloading and promoting load balancing.

Answer

Offers better efficiency than consistent hashing, making it suitable for smaller datasets.

Answer

Uses a different hash function, resulting in distinct data distribution patterns.

Answer

Is not suitable for handling large datasets due to its computational complexity.

Question 31

What is the primary purpose of a hash function?

Accepted Answer

To transform an input of arbitrary size into a fixed-length output value

Answer

To resolve collisions in a hash table

Answer

To store data in a hash table

Question 32

What is a key difference between hash tables and binary search trees?

Accepted Answer

Hash tables use hash functions to store and retrieve data, while binary search trees use a sorted structure for efficient searching.

Answer

Hash tables are always faster than binary search trees.

Question 33

What is the load factor of a hash table?

Accepted Answer

The ratio of the number of elements stored in the hash table to the table size

Answer

The number of collisions that occur in the hash table

Answer

The average number of elements stored in each bucket of the hash table

Question 34

Which of the following is NOT a benefit of using hashing techniques?

Accepted Answer

Increased memory consumption

Answer

Efficient search and insert operations

Answer

Effective storage for large datasets

Answer

Rapid data retrieval

Question 35

What is the primary role of a hash function in a hashing system?

Accepted Answer

Maps data keys to unique indices in a hash table

Answer

Resolves collisions that occur during hashing

Answer

Stores data elements in a specified order

Answer

Generates random numbers for key generation

Question 36

Which of the following is a practical application of hashing?

Accepted Answer

Database indexing for efficient data retrieval

Answer

Sorting algorithms

Answer

Tree traversal algorithms

Answer

Graph traversal algorithms

Question 37

What is the term used to describe the ratio of elements to the table size in a hash table?

Accepted Answer

Load factor

Answer

Density

Answer

Usage percentage

Answer

Fill ratio

Question 38

What is the primary objective of using double hashing in a hashing system?

Accepted Answer

Reduces the clustering of keys in a hash table, improving search efficiency

Answer

Increases the size of the hash table to accommodate more data

Answer

Improves the worst-case search time complexity

Answer

Resolves collisions using chaining

Question 39

Which of the following is a benefit of using hashing?

Accepted Answer

Efficient data retrieval

Answer

Increased storage space

Answer

Slow lookup times

Answer

Improved data security

Question 40

Which of the following is a common hash function?

Accepted Answer

MD5

Answer

Recursion

Answer

Bubble sort

Answer

Binary search

Question 41

Which of the following collision resolution techniques involves storing multiple elements in the same slot?

Accepted Answer

Chaining

Answer

Quadratic probing

Answer

Linear probing

Answer

Open addressing

Question 42

Which of the following is a suitable load factor for a hash table?

Accepted Answer

Between 0.5 and 0.75

Answer

Greater than 1

Answer

Less than 0.25

Question 43

What is the primary purpose of a hash table?

Accepted Answer

To store and retrieve data efficiently based on a key

Answer

To compress data for storage

Answer

To sort data in ascending order

Question 44

What is the goal of a hash function?

Accepted Answer

To map a large set of inputs to a smaller set of fixed-size outputs

Answer

To generate random numbers

Answer

To search for specific elements in a data structure

Question 45

Which of the following is an application of hashing?

Accepted Answer

Storing user passwords in a database

Answer

Generating random numbers

Answer

Sorting large amounts of data

Answer

Finding the smallest element in a list

Question 46

Define a hash table.

Accepted Answer

A data structure that uses a hash function to map keys to values

Answer

A linked list that stores data in sorted order

Answer

A binary tree that allows efficient search and insert operations

Question 47

Which of the following is a significant advantage of using a hash table?

Accepted Answer

Enhanced speed in data retrieval

Answer

Elimination of duplicate data entries

Answer

Assured collision-free storage

Answer

Reduced memory consumption

Question 48

What is the primary function of a hash function?

Accepted Answer

Mapping a key to a specific index within the hash table

Answer

Calculating the size of the hash table

Answer

Storing data in a sorted arrangement

Answer

Identifying duplicate data entries

Question 49

Which of the following is NOT a disadvantage associated with using chaining for collision resolution?

Accepted Answer

Lower memory consumption

Answer

Potential for creating long chains

Answer

Potential for reduced performance

Question 50

What is the term used to describe the ratio of stored elements to the size of the hash table?

Accepted Answer

Load factor

Answer

Fill factor

Answer

Utilization ratio

Question 51

What is the fundamental difference between a perfect and a non-perfect hash function?

Accepted Answer

A perfect hash function ensures no collisions, while a non-perfect hash function may result in collisions.

Answer

A perfect hash function is computationally more efficient than a non-perfect hash function.

Question 52

What is the average time complexity of searching for an element in a hash table that employs chaining for collision resolution?

Accepted Answer

O(1) on average, O(n) in the worst case

Answer

O(1) in all cases

Answer

O(log n) in all cases

Answer

O(n) in all cases