Hash table applications in Data Structures Theory - Mini Project: Build & Apply

Hash Table Applications

📖 Scenario: You are organizing a small library's book collection. You want to quickly find if a book is available by its title and also count how many times each author appears in the collection.

🎯 Goal: Build a simple hash table application using a dictionary to store book titles and authors, then count the number of books per author.

📋 What You'll Learn

Create a dictionary called books with exact book titles as keys and author names as values

Create a variable called author_counts to store the count of books per author

Use a for loop with variables title and author to iterate over books.items()

Update author_counts to count how many books each author has

Add a final step to complete the author_counts dictionary with all authors and their counts

💡 Why This Matters

🌍 Real World

Libraries, bookstores, and inventory systems use hash tables to quickly find and count items like books or products.

💼 Career

Understanding hash table applications is important for roles in software development, data analysis, and database management where fast data lookup and counting are common tasks.

1

Create the books dictionary

Create a dictionary called books with these exact entries: 'The Hobbit': 'J.R.R. Tolkien', '1984': 'George Orwell', 'Pride and Prejudice': 'Jane Austen', 'The Silmarillion': 'J.R.R. Tolkien', 'Animal Farm': 'George Orwell'.

Data Structures Theory

# Create the books dictionary with titles and authors
# Your code here

Need a hint?

Use curly braces {} to create a dictionary with the exact book titles as keys and authors as values.

2

Create the author_counts dictionary

Create an empty dictionary called author_counts to store the count of books per author.

Data Structures Theory

books = {
    'The Hobbit': 'J.R.R. Tolkien',
    '1984': 'George Orwell',
    'Pride and Prejudice': 'Jane Austen',
    'The Silmarillion': 'J.R.R. Tolkien',
    'Animal Farm': 'George Orwell'
}
# Create an empty dictionary called author_counts
# Your code here

Need a hint?

Use {} to create an empty dictionary named author_counts.

3

Count books per author

Use a for loop with variables title and author to iterate over books.items(). Inside the loop, update author_counts to add 1 to the count for each author. If the author is not yet in author_counts, add them with a count of 1.

Data Structures Theory

books = {
    'The Hobbit': 'J.R.R. Tolkien',
    '1984': 'George Orwell',
    'Pride and Prejudice': 'Jane Austen',
    'The Silmarillion': 'J.R.R. Tolkien',
    'Animal Farm': 'George Orwell'
}
author_counts = {}
# Use a for loop to count books per author
# Your code here

Need a hint?

Use for title, author in books.items(): to loop through the dictionary. Use an if statement to check if the author is already in author_counts.

4

Complete the author_counts dictionary

Add a final line to ensure author_counts contains all authors from books with their correct counts. This completes the hash table application for counting books per author.

Data Structures Theory

books = {
    'The Hobbit': 'J.R.R. Tolkien',
    '1984': 'George Orwell',
    'Pride and Prejudice': 'Jane Austen',
    'The Silmarillion': 'J.R.R. Tolkien',
    'Animal Farm': 'George Orwell'
}
author_counts = {}
for title, author in books.items():
    if author in author_counts:
        author_counts[author] += 1
    else:
        author_counts[author] = 1
# Finalize the author_counts dictionary
# Your code here

Need a hint?

The counting logic is complete. This final step confirms the dictionary is ready for use.