Description
1. Introduction
In this exercise, we will complete one Python function to check whether a given number is a
Happy Number or not.
2. Objectives
The purpose of this assignment is to give you experience in:
• Using mathematical calculations in Python.
• Refreshing knowledge on function and loops in Python.
• Refreshing knowledge on string operations and set operations.
Note: Before you start, if you are not familiar with string operations, if/else statement, for loop, while
loop or function in Python, you are recommended to review the sample codes we covered in lecture first.
3. Background
3.1. Happy Numbers
A happy number is a number 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 either 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. Please see the following examples.
• 13 is a happy number since
1
2 + 3
2 = 1 + 9 = 10,
1
2 + 0
2 = 1 + 0 = 1
• 85 is an unhappy number since
8
2 + 5
2 = 64 + 25 = 89,
8
2 + 9
2 = 64 + 81 = 145,
1
2 + 4
2 + 5
2 = 1 + 16 + 25 = 42,
4
2 + 2
2 = 16 + 4 = 20,
2
2 + 0
2 = 4,
4
2 = 16,
1
2 + 6
2 = 1 + 36 = 37,
3
2 + 7
2 = 9 + 49 = 58,
5
2 + 8
2 = 25 + 64 = 89, which is a repeated result
In the examples above, we can find that a good way to check whether a number is a happy
number is to check whether there is a result equal to 1 or a repeated result greater than 1
through the iterative process.
4. Assignment
When you are reading this assignment, you must have already downloaded the skeleton zip file.
In the zip file, you can find a skeleton code, named happy.py. All you need to do is to complete
the skeleton code based on the instructions and submit it to the Mimir system.
4.1. Happy number checking function
Now, open the skeleton code. You can see one function named happy(number), which is the
only function that you need to complete. This function should return True (Boolean value)
when the input is a happy number or return False when the input is not a happy number.
In order to check a large number, the type of the input parameter variable should be string
instead of int. In other words, this function is to check whether a positive integer represented
by a string is a happy number or not.
For example, a typical string input may look like “2345678901234567899999”. Note the
number represented by this string could be larger than any long integers. You need to write
your own code to hand this string. Variable type conversion and set operation can be of help.
In the skeleton code, the statements below the function are designed to check the functionality
of your code by outputting all the happy numbers up to 1000.
5. Submit your work to Mimir
Submit your code to Mimir after you complete your code. The Mimir will automatically check
the output of your code and grade your submission. You can submit your code to Mimir up to
30 times to refresh your existing score before the submission deadline.
6. Due date
This lab assignment is worth 4 points in the final grade. It will be due by 11:59pm on Sep 18
th
2017. A penalty of 10% per day will be deducted from your grade, starting at 12:00am.
