Python: Find and print the first 10 happy numbers

Python Basic - 1: Exercise-67 with Solution

First 10 Happy Numbers

From Wikipedia,
A happy number is defined by the following process:
Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers, while those that do not end in 1 are unhappy numbers.
Write a Python program to find and print the first 10 happy numbers.

Sample Solution:

Python Code:

# Function to check if a number is a Happy Number
def happy_numbers(n):
    past = set()  # Set to store previously encountered numbers during the process
    while n != 1:  # Continue the process until the number becomes 1 (a Happy Number) or a cycle is detected
        n = sum(int(i) ** 2 for i in str(n))  # Calculate the sum of squares of each digit in the number
        if n in past:  # If the current number has been encountered before, it forms a cycle
            return False  # The number is not a Happy Number
        past.add(n)  # Add the current number to the set of past numbers
    return True  # If the process reaches 1, the number is a Happy Number

# Print the first 10 Happy Numbers less than 500
print([x for x in range(500) if happy_numbers(x)][:10])

Sample Output:

[1, 7, 10, 13, 19, 23, 28, 31, 32, 44]

Explanation:

Here is a breakdown of the above Python code:

• Define a function named "happy_numbers()" that takes a number 'n' as input.
• Initialize a set called 'past' to keep track of previously encountered numbers during the process.
• Use a while loop to continue the process until the number becomes 1 (a Happy Number) or a cycle is detected.
• Inside the loop, calculate the sum of the squares of each digit in the current number.
• Check if the current number has been encountered before. If yes, it forms a cycle, and the number is not a Happy Number.
• Add the current number to the set of past numbers.
• Return 'True' if the process reaches 1, indicating that the number is a Happy Number.
• Use a list comprehension to generate the first 10 Happy Numbers less than 500 and print the result.

Visual Presentation:

Flowchart:

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a Write a Python program to check whether a number is "happy" or not.
Next: Write a Python program to count the number of prime numbers less than a given non-negative number.