Hash Functions and Hash Tables: Master Data Structures and Algorithms

Question 1

Which of the following accurately compares the advantages and disadvantages of open addressing and chaining in collision resolution?

Accepted Answer

Open addressing is more space-efficient, while chaining performs better with numerous collisions.

Answer

Chaining is ideal for large hash tables, while open addressing is better for smaller ones.

Answer

Open addressing and chaining have comparable performance and memory usage.

Question 2

Which data structure is commonly used to implement a hash table?

Accepted Answer

Array

Answer

Linked list

Answer

Binary search tree

Answer

Heap

Question 3

Which collision resolution technique involves creating a linked list of values in the same hash bucket?

Accepted Answer

Chaining

Answer

Open addressing

Answer

Double hashing

Answer

Linear probing

Question 4

The process of converting a key into a numerical value that is used as an index into a hash table is known as:

Accepted Answer

Hashing

Answer

Collisions

Answer

Load balancing

Answer

Probing

Question 5

Which of the following is not a common approach to resolving collisions in open addressing?

Accepted Answer

Chaining

Answer

Linear probing

Answer

Quadratic probing

Answer

Double hashing

Question 6

Bloom filters are a type of hash table that is used primarily for:

Accepted Answer

Estimating the probability of an element being in a set

Answer

Storing large amounts of data in a memory-efficient way

Answer

Speeding up database queries

Answer

Implementing a distributed hash table

Question 7

What is the primary purpose of collision resolution techniques in hash tables?

Accepted Answer

To manage keys with identical hash values

Answer

To prevent duplicate keys

Answer

To map keys uniquely to memory locations

Answer

To enhance search efficiency

Question 8

Which collision resolution technique involves maintaining a linked list of keys with the same hash value?

Accepted Answer

Chaining

Answer

Linear probing

Answer

Quadratic probing

Answer

Double hashing

Question 9

What is the definition of load factor in the context of hash tables?

Accepted Answer

The ratio of keys to the table size

Answer

The number of collisions in the table

Answer

The average number of keys per bucket

Answer

The maximum capacity of the table

Question 10

What is the fundamental difference between a hash table and a binary search tree?

Accepted Answer

Hash tables use hashing for finding elements, while binary search trees use binary search.

Answer

Hash tables are more suitable for large datasets, while binary search trees are more efficient for small datasets.

Answer

Hash tables can only handle integer keys, while binary search trees can handle any data type.

Answer

Binary search trees are simpler to implement than hash tables.

Question 11

Which collision resolution technique involves linking multiple keys in the same slot?

Accepted Answer

Chaining (Linked List)

Answer

Linear probing

Answer

Quadratic probing

Answer

Double hashing

Question 12

What is the primary purpose of a collision resolution technique?

Accepted Answer

To improve the efficiency of hash table operations

Answer

To eliminate collisions in a hash table

Answer

To prevent data loss

Answer

To ensure data integrity

Question 13

Which collision resolution technique involves creating a linked list for elements that hash to the same index?

Accepted Answer

Chaining

Answer

Linear probing

Answer

Quadratic probing

Answer

Double hashing

Question 14

What does the load factor of a hash table represent?

Accepted Answer

The ratio of elements to available slots in the table

Answer

The number of collisions in the table

Answer

The average number of elements per slot

Answer

The maximum number of elements that can be stored in the table

Question 15

What is the primary purpose of a collision resolution technique?

Accepted Answer

To handle situations where two or more keys hash to the same index

Answer

To enhance the efficiency of hash table operations

Answer

To minimize the number of hash collisions

Answer

To prevent data loss

Question 16

What is the primary advantage of using a hash table over a linked list?

Accepted Answer

Faster lookup time (O(1) on average)

Answer

Less memory usage

Answer

Easier implementation

Answer

Better organization of data

Question 17

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

Accepted Answer

To measure the fullness of the hash table and guide decisions on resizing

Answer

To determine the optimal size of the hash table

Answer

To improve the performance of collision resolution

Answer

To prevent data loss

Question 18

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

Accepted Answer

Reversibility of the mapping

Answer

Uniform distribution of output values

Answer

Efficient computation

Answer

Resistance to collision attacks

Question 19

In a hash table, which collision resolution technique involves storing colliding elements in a linked list?

Accepted Answer

Chaining

Answer

Open addressing

Answer

Double hashing

Answer

Linear probing

Question 20

What is the worst-case time complexity of searching for an element in a hash table using linear probing?

Accepted Answer

O(n)

Answer

O(1)

Answer

O(log n)

Answer

O(n^2)

Question 21

Which of the following is a primary advantage of utilizing hash functions in data structures?

Accepted Answer

Enhanced search and retrieval efficiency

Answer

Reduced memory consumption

Answer

Improved data security

Answer

Simplified data organization

Question 22

Which collision resolution technique involves creating a linked list for elements that hash to the same slot in a hash table?

Accepted Answer

Chaining

Answer

Linear probing

Answer

Quadratic probing

Question 23

In linear probing, what is the worst-case scenario for the number of probes required to insert an element into a hash table?

Accepted Answer

Table size

Answer

Constant

Answer

Square root of table size

Answer

Log of table size

Question 24

Which of the following is NOT an advantage of using a hash table compared to a binary search tree?

Accepted Answer

Supports sorted data

Answer

Faster lookup for large datasets

Answer

Better memory utilization

Answer

More efficient insertion and deletion

Question 25

When selecting a hash function for a hash table, which factor should NOT be considered?

Accepted Answer

Size of the input data

Answer

Computational complexity

Answer

Distribution of the input data

Answer

Desired performance characteristics

Question 26

Which of the following applications is a good use case for a hash table?

Accepted Answer

Storing unique usernames for user accounts

Answer

Implementing a priority queue

Answer

Representing a graph

Answer

Maintaining a sorted list of integers

Question 27

Consider a hash table with a load factor of 0.75 and 100 elements. What is the maximum number of additional elements that can be inserted before resizing is necessary?

Accepted Answer

132

Answer

50

Answer

100

Answer

200

Question 28

Which of the following is a commonly used collision resolution technique in hash tables?

Accepted Answer

Linear probing.

Answer

Breadth-first search.

Answer

Depth-first search.

Answer

Hill Climbing.

Question 29

What is the primary purpose of utilizing a hash table data structure?

Accepted Answer

To efficiently store and retrieve data based on key-value pairs.

Answer

To sort a sequence of numbers in ascending order.

Answer

To determine the shortest path within a graph.

Question 30

Which of the following is a key advantage of using hash tables?

Accepted Answer

Enhanced search and retrieval efficiency.

Answer

Guaranteed absence of collisions.

Answer

Reduced memory consumption.

Question 31

What does the load factor of a hash table represent?

Accepted Answer

The ratio of the number of elements to the table's capacity.

Answer

The average number of elements in each bucket.

Answer

The total number of collisions that have occurred.

Question 32

Which of the following algorithms is commonly used for hashing?

Accepted Answer

SHA-256.

Answer

Dijkstra's algorithm.

Answer

Prim's algorithm.

Answer

Bellman-Ford algorithm.

Question 33

What is a key benefit of employing double hashing as a collision resolution method?

Accepted Answer

Reduced likelihood of clustering.

Answer

Enhanced search performance.

Answer

Guaranteed prevention of collisions.

Question 34

Which of the following is a potential drawback of utilizing hash tables?

Accepted Answer

The possibility of hash collisions.

Answer

Excessive memory requirements.

Answer

Slow search performance.

Answer

Complex implementation.

Question 35

What is the fundamental purpose of a hash function?

Accepted Answer

To convert arbitrary data into a fixed-size output.

Answer

To sort data in ascending order.

Answer

To generate random numbers.

Answer

To compress data.

Question 36

Which of the following drawbacks is commonly associated with hash tables?

Accepted Answer

Potential for hash collisions leading to performance degradation

Answer

Difficulty in handling duplicate keys

Answer

Vulnerability to brute-force attacks due to limited key space

Answer

High memory consumption even with low data density

Question 37

Which operation benefits from the efficient indexing capabilities of hash tables compared to binary search trees?

Accepted Answer

Searching for a specific element

Answer

Inserting a new element

Answer

Deleting an existing element

Question 38

Explain the fundamental difference between chaining and linear probing as collision resolution methods.

Accepted Answer

Chaining uses linked lists to handle collisions, while linear probing searches sequentially for an empty slot.

Answer

Chaining stores overflow elements in a separate array, whereas linear probing overwrites existing data.

Question 39

When is a hash table considered to be at its overflow point?

Accepted Answer

When the load factor exceeds a predetermined threshold, indicating a high probability of collisions

Answer

When all the slots in the table are occupied

Answer

When the number of elements in the table reaches its maximum capacity

Answer

When the average search time surpasses a certain limit

Question 40

True or False: Hashing is a reliable method for securely encrypting sensitive data.

Accepted Answer

False

Answer

N/A

Answer

None of the above

Answer

True

Question 41

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

Accepted Answer

To map a key to a unique index within a fixed-size array

Answer

To sort data in ascending or descending order

Answer

To generate a random number for use in data retrieval

Question 42

Which collision resolution technique involves storing multiple key-value pairs in the same array slot using a linked list?

Accepted Answer

Chaining

Answer

Quadratic probing

Answer

Double hashing

Answer

Linear probing

Question 43

In a well-designed hash table, what is the expected time complexity of a successful search operation?

Accepted Answer

O(1)

Answer

O(n)

Answer

O(log n)

Answer

O(n^2)

Question 44

What is a potential drawback of using a hash function based on a simple modulo operation?

Accepted Answer

Hash collisions

Answer

Reduced data security

Answer

Slow hash computation

Answer

Increased memory consumption

Question 45

To minimize collisions in a hash table, what should the load factor ideally be?

Accepted Answer

Less than 1

Answer

Greater than 1

Answer

Exactly 1

Question 46

Which of the following is suitable for use as a hash function for strings?

Accepted Answer

MD5

Answer

Linear probing

Answer

Quadratic probing

Question 47

What is the primary reason for using a bloom filter in conjunction with a hash table?

Accepted Answer

To reduce false positives in set membership queries

Answer

To eliminate hash collisions

Answer

To enhance search performance

Question 48

When designing a hash function for a specific application, which factor is of utmost importance?

Accepted Answer

The distribution of input keys

Answer

The size of the hash table

Answer

The operating system of the computer

Answer

The programming language used

Question 49

What is the fundamental purpose of a hash map in data structures?

Accepted Answer

To provide efficient storage and retrieval of key-value pairs using keys as lookup indices

Answer

To perform mathematical calculations

Answer

To sort data in ascending order

Question 50

Which characteristic is LEAST desirable for a good hash function?

Accepted Answer

Mapping similar keys to similar hash values.

Answer

Easy to implement in code.

Answer

Producing a uniform distribution of hash values.

Answer

Simple and efficient to compute.

Question 51

What collision resolution method utilizes linked lists to manage colliding keys?

Accepted Answer

Chaining

Answer

Open addressing

Answer

Double hashing

Answer

Linear probing

Question 52

Which collision resolution technique searches for the next available slot in the hash table in a sequential manner?

Accepted Answer

Linear probing

Answer

Double hashing

Answer

Chaining

Answer

Cuckoo hashing

Question 53

The average number of elements examined during a search in a hash table is directly related to:

Accepted Answer

Load factor

Answer

Table size

Answer

Collision rate

Answer

Hash function efficiency

Question 54

In a hash table, which operation typically exhibits the worst-case time complexity?

Accepted Answer

Search, Insert, and Delete can all degrade to O(n) in the worst case.

Answer

Search for a non-existent key

Answer

Delete

Answer

Insert

Question 55

What is the maximum valid index within a hash table of size 'n'?

Accepted Answer

n - 1

Answer

n / 2

Answer

It depends on the hash function

Answer

n

Question 56

What technique is frequently employed to increase the capacity of a hash table when it reaches a high load factor?

Accepted Answer

Rehashing

Answer

Chaining

Answer

Linear probing

Answer

Open addressing

Question 57

What is the time complexity, in Big O notation, for searching an element in a hash table using separate chaining, assuming a uniformly distributed hash function?

Accepted Answer

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

Answer

O(n^2)

Answer

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

Answer

O(log n)

Question 58

Which hash function is generally NOT considered suitable for hashing strings due to its potential for uneven distribution with string data?

Accepted Answer

Division method using a prime number close to the table size

Answer

Fowler-Noll-Vo (FNV) hash function

Answer

DJB2 hash function

Answer

Multiplication method

Question 59

What is the primary application of a Bloom filter?

Accepted Answer

Probabilistically testing if an element is a member of a set

Answer

Resolving collisions in hash tables

Answer

Generating cryptographic hash values

Answer

Compressing data