Class7.md

Class 7: Sets & Circular Buffers

Minute-by-Minute [OPTIONAL]

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Elapsed	Time	Activity
0:00	0:05	Objectives
0:05	0:15	Overview
0:20	0:45	In Class Activity I
1:05	0:10	BREAK
1:15	0:45	In Class Activity II
TOTAL	2:00

Learning Objectives (5 min)

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By this end of this lesson, students should be able to...

1. Explain what a set is and what some varitions of a set are, such as a multiset
2. Explain other types of queues such as a circuluar buffer
3. Practice implementing more abstract data types backed by a data structure of their choice

Topics

• Abstract data types: set, multiset (bag)
• Concrete data structures: hash table, circular buffer (circular queue, ring buffer)
• Set operations

Resources

• Read Vaidehi Joshi's article on sets and their use in databases with beautiful drawings and excellent examples

Challenges

• Implement Set class (abstract data type backed by data structure of your choice) with the following set operations as instance methods and properties:
  • __init__(elements=None) - initialize a new empty set structure, and add each element if a sequence is given
  • size - property that tracks the number of elements in constant time
  • contains(element) - return a boolean indicating whether element is in this set
  • add(element) - add element to this set, if not present already
  • remove(element) - remove element from this set, if present, or else raise KeyError
  • union(other_set) - return a new set that is the union of this set and other_set
  • intersection(other_set) - return a new set that is the intersection of this set and other_set
  • difference(other_set) - return a new set that is the difference of this set and other_set
  • is_subset(other_set) - return a boolean indicating whether other_set is a subset of this set
• Write unit tests to ensure the Set class is robust
  • Include test cases for each class instance method
• Annotate all instance methods with complexity analysis of running time and space (memory)
• Compare the behaviors of your Set class to those of the Python set type and Swift Set type

Stretch Challenges

• Implement CircularBuffer class (backed by dynamic array) with the following instance methods and properties:
  • __init__(max_size) - initialize a new circular buffer that can store at most max_size items
  • size - property that tracks the number of items in the buffer
  • is_empty - check if the buffer is empty
  • is_full - check if the buffer is full
  • enqueue(item) - insert item at the back of the buffer
  • front - return the item at the front of the buffer
  • dequeue - remove and return the item at the front of the buffer
• Annotate enqueue and dequeue methods with running time complexity analysis
• Write unit tests to ensure the CircularBuffer class is robust
  • Include test cases for each class instance method and property
• Annotate enqueue and dequeue methods with running time complexity analysis