Collision handling (chaining) in Data Structures Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is collision handling in hash tables?

Collision handling is a method used to resolve situations when two different keys hash to the same index in a hash table.

beginner

Explain the chaining method for collision handling.

Chaining handles collisions by storing all elements that hash to the same index in a linked list or chain at that index.

intermediate

Why is chaining considered a simple and effective collision handling technique?

Because it allows multiple elements to be stored at the same index without overwriting, and it is easy to implement using linked lists.

intermediate

What happens when many keys collide and are stored in the same chain?

The chain becomes longer, which can slow down search, insertion, and deletion operations because they require traversing the list.

advanced

How can the performance of chaining be improved in a hash table?

By keeping the load factor low through resizing the table or using a good hash function to distribute keys evenly.

What does chaining use to handle collisions in a hash table?

A Linked lists at each index

B Open addressing

C Rehashing

D Binary search trees

Chaining uses linked lists (or similar structures) at each index to store multiple elements that hash to the same slot.

What is a disadvantage of chaining when many keys collide?

A Hash function stops working

B The hash table size decreases

C Keys get lost

D Chains become long, slowing down operations

Long chains mean more elements to check during search, insertion, or deletion, which slows down these operations.

Which of the following is NOT a benefit of chaining?

A Requires no extra memory

B Handles unlimited collisions gracefully

C Allows easy insertion

D Simple to implement

Chaining requires extra memory for linked lists, so it does need additional memory beyond the array.

How can chaining performance be improved?

A By increasing the load factor

B By using a poor hash function

C By resizing the hash table to reduce load

D By storing all keys in one chain

Resizing the table reduces the load factor, which shortens chains and improves performance.

In chaining, what data structure is commonly used to store collided elements?

A Array

B Linked list

C Stack

D Queue

Linked lists are commonly used because they allow easy insertion and traversal of collided elements.

Describe how collision handling by chaining works in a hash table.

Think about what happens when two keys hash to the same place.

Explain the advantages and disadvantages of using chaining for collision handling.

Consider both ease of use and performance impact.