CMU 15-112 Summer 2020: Fundamentals of Programming and Computer Science
Homework 1 (Due Tue 19-May, at 5pm)

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• This assignment is SOLO. This means you may not look at other student's code or let other students look at your code for these problems. See the syllabus for details.


• To start:
  1. Create a folder named 'hw1'
  2. Download hw1.py and cs112_m20_week1_linter.py to that folder
  3. Edit hw1.py using VSCode
  4. When you are ready, submit hw1.py to Autolab. For this hw, you may submit up to 20 times (which is way more than you should require), but only your last submission counts.
• Do not use string indexing, loops, lists, or recursion in this assignment.
• Do not hardcode the test cases in your solutions.
• Hint: The starter hw1.py file includes test functions. When you run your file, problems will be tested in order. If you wish to temporarily bypass specific tests (say, because you have not yet completed some functions), you can comment out individual test function calls at the bottom of your file in testAll(). However, be sure to uncomment and test everything together before you submit! Ask a TA if you need help with this.

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Important note about spiciness levels!
Note: this homework has 2 levels: Medium and Spicy.
50 points of hw1 come from collab1. 20 points of hw1 come from the CT and ROC practice.
This leaves 30 points to gain from either getKthDigit or colorBlender. Choose the problem at the level that is most appropriate for you.

1. CT & ROC Practice [20pts - Required]
   Download day1-ct-rc-runner.zip, unzip it, and run go.py
   Log in with the username and password you received from us.
   For full credit, you must complete a CT problem in under 5 minutes and an ROC problem in under 5 minutes.
   For every minute it takes you to complete the problem over 5 minutes you will lose 20% of the score for that problem.
   Only your best score is counted.
   You have unlimited attempts to complete each type of problem in the time limit.
   Important: To receive any credit, you must quickly upload a picture of your scrap work and your submission confirmation to this form after getting a correct answer.
   Your picture should look something like this. Notice that clearly visible in this image are:
   1. Your scrap work and answer
   2. The CT RESULTS table including the problem statement, correct answer, and your answer
   
   
2. getKthDigit(n, k) [30pts - Medium]
   Write the function getKthDigit(n, k) that takes a possibly-negative int n and a non-negative int k, and returns the kth digit of n, starting from 0, counting from the right. So:
      getKthDigit(789, 0) returns 9
      getKthDigit(789, 2) returns 7
      getKthDigit(789, 3) returns 0
      getKthDigit(-789, 0) returns 9
   


3. colorBlender(rgb1, rgb2, midpoints, n) [30pts - Spicy]
   This problem implements a color blender, inspired by this tool. In particular, we will use it with integer RGB values (it also does hex values and RGB% values, but we will not use those modes). Note that RGB values contain 3 integers, each between 0 and 255, representing the amount of red, green, and blue respectively in the given color, where 255 is "entirely on" and 0 is "entirely off".
   
   For example, consider this case. Here, we are combining crimson (rgb(220, 20, 60)) and mint (rgb(189, 252, 201)), using 3 midpoints, to produce this palette (using our own numbering convention for the colors, starting from 0, as the tool does not number them):
   
   
   color0: rgb(220, 20, 60) color1: rgb(212, 78, 95) color2: rgb(205, 136, 131) color3: rgb(197, 194, 166) color4: rgb(189, 252, 201)
   
   There are 5 colors in the palette because the first color is crimson, the last color is mint, and the middle 3 colors are equally spaced between them.
   
   So we could ask: if we start with crimson and go to mint, with 3 midpoints, what is color #1? The answer then would be rgb(212, 78, 95).
   
   One last step: we need to represent these RGB values as a single integer. To do that, we'll use the first 3 digits for red, the next 3 for green, the last 3 for blue, all in base 10 (decimal, as you are accustomed to). Hence, we'll represent crimson as the integer 220020060, and mint as the integer 189252201.
   
   With all that in mind, write the function colorBlender(rgb1, rgb2, midpoints, n), which takes two integers representing colors encoded as just described, a non-negative integer number of midpoints, and a non-negative integer n, and returns the nth color in the palette that the tool creates between those two colors with that many midpoints. If n is out of range (too small or too large), return None.
   
   For example, following the case above: colorBlender(220020060, 189252201, 3, 1) returns 212078095
   
   Hints: RGB values must be ints, not floats. Also, remember to use roundHalfUp(n) instead of round(n) when calculating midpoint colors.