Why Hash Map Exists and What Problem It Solves in DSA Python - See It Work

Why Hash Map Exists and What Problem It Solves

📖 Scenario: Imagine you have a big box of keys and you want to find the right key quickly. Searching one by one takes too long. A hash map helps you find the right key fast, like having a special map that tells you exactly where each key is.

🎯 Goal: You will create a simple phone book using a dictionary to see how a hash map helps find phone numbers quickly by name.

📋 What You'll Learn

Create a dictionary called phone_book with exact entries for names and phone numbers

Create a variable called search_name with the exact value to look up

Use a for loop with variables name and number to find the phone number for search_name

Print the phone number found or a message if the name is not in the phone book

💡 Why This Matters

🌍 Real World

Hash maps are used in phone books, contact lists, and many apps to find information quickly by a key like a name or ID.

💼 Career

Understanding hash maps helps in software development, especially when working with databases, caching, and fast data retrieval.

1

Create the phone book dictionary

Create a dictionary called phone_book with these exact entries: 'Alice': '555-1234', 'Bob': '555-5678', 'Charlie': '555-8765'

DSA Python

# Create the phone_book dictionary with given entries
# Your code here

Hint

Use curly braces {} to create the dictionary with keys as names and values as phone numbers.

2

Set the name to search

Create a variable called search_name and set it to the string 'Bob'

DSA Python

phone_book = {'Alice': '555-1234', 'Bob': '555-5678', 'Charlie': '555-8765'}
# Create the search_name variable with value 'Bob'
# Your code here

Hint

Assign the string 'Bob' to the variable search_name.

3

Find the phone number using a loop

Use a for loop with variables name and number to iterate over phone_book.items(). Inside the loop, check if name equals search_name. If yes, save number to a variable called found_number and break the loop. If no match is found, set found_number to None before the loop.

DSA Python

phone_book = {'Alice': '555-1234', 'Bob': '555-5678', 'Charlie': '555-8765'}
search_name = 'Bob'
# Initialize found_number to None
# Use a for loop to find the number for search_name
# Your code here

Hint

Start with found_number = None. Then loop over phone_book.items(). Use if name == search_name to find the number and break the loop.

4

Print the result

Use an if statement to check if found_number is not None. If it is not None, print found_number. Otherwise, print "Name not found".

DSA Python

phone_book = {'Alice': '555-1234', 'Bob': '555-5678', 'Charlie': '555-8765'}
search_name = 'Bob'
found_number = None
for name, number in phone_book.items():
    if name == search_name:
        found_number = number
        break
# Print found_number if found, else print "Name not found"
# Your code here

Hint

Use if found_number is not None to decide what to print.