drills.md

Week 1 Drills

For this week's drills we will be playing a game called "Kyrel".

In this game, you will be given a row and asked to transform it into a different row. For instance, you might be given a row with five empty cells and asked to draw a blue dot in the right-most cell. Since you always start in the left-most cell (the default starting position), you'll need to move before you can draw.

Methods

The following special methods are available for traversing/transforming the row:

• moveRight();
• moveLeft();
• useGreen();
• useBlue();
• draw();
• erase();
• onGreen();
• onBlue();

Example Problem

Write a program which draws a green circle at the end of the row.

    moveRight();
    moveRight();
    moveRight();
    moveRight();
    useGreen();
    draw();

This would result in the following transformation:

 ['.', '.', '.', '.', '.'] // start row (initial state)
 ['.', '.', '.', '.', 'g'] // end row (end state)

• 'b' means a "blue" dot
• 'g' means a "green" dot
• '.' means an empty cell

Rules

• You must always begin in the left-most cell. This is your default starting position.
• You cannot fall off the board / row. If you try to move past the last cell, you just remain in the same cell.
• You must choose a color before you can draw.
• You do not need to erase before drawing -- you can overwrite a cell's color.

Goals

• Abstract the problem. Does your solution work for only a specific case, or does it work for all cases?
• "Don't repeat yourself" -- See a lot of repetition in your code? Maybe it's time to refactor.
• Be efficient. How many steps do your instructions take? How does the number of steps compare to the number of cells in the row? (What if the row got longer!?)

Kyrel Challenges

Day 1 Challenges -- intro to commands

0. turn_3rd_cell_blue - solution

   start: ['.', '.', '.', '.', '.']
   finish: ['.', .', 'b', '.', '.']

1. erase_3rd_cell - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['b', 'b', '.', 'b', 'b']

2. every_other_erase - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['b', '.', 'b', '.', 'b']

3. every_other_blue - solution

start: ['g', 'g', 'g', '.', '.']
finish: ['g', 'b', 'g', 'b', '.']

4. move_start_to_finish - solution

start: ['b', '.', '.', '.', '.']
finish: ['.', '.', '.', '.', 'b']

start: ['g', '.', '.', '.', '.']
finish: ['.', '.', '.', '.', 'g']

start: ['.', '.', '.', '.', '.']
finish: ['.', '.', '.', '.', '.']

Day 2 Challenges -- basic for loops & conditionals

0. all_blue - solution

start: ['.', '.', '.', '.', '.']
finish: ['b', 'b', 'b', 'b', 'b']

1. all_first_color - solution

start: ['b', '.', '.', '.', '.']
finish: ['b', 'b', 'b', 'b', 'b']

start: ['g', '.', '.', '.', '.']
finish: ['g', 'g', 'g', 'g', 'g']

2. n_in_a_row - solution

start: ['.', '.', '.', '.', '.']
finish: ['b', 'b', '.', '.', '.'] (given n is 2)
finish: ['b', 'b', 'b', '.', '.'] (given n is 3)

3. every_even_erase - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['.', 'b', '.', 'b', '.']

4. every_odd_erase - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['b', '.', 'b', '.', 'b']

Day 3 Challenges -- More Loops

Before you get started on today's exercises, please download the Kyrel App, either by cloning it, or downloading the zip file.

0. every_even_erase - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['.', 'b', '.', 'b', '.']

2. every_n_erase - solution

start: ['b', 'b', 'b', 'b', 'b']
finish: ['b', 'b', 'b', '.', 'b'] (given n is 4)
finish: ['b', 'b', 'b', 'b', '.'] (given n is 5)

3. move_the_blue_dot_one_to_the_right - solution

start: ['.', '.', 'b', '.', '.']
finish: ['.', '.', '.', 'b', '.']

start: ['g', 'b', '.', '.', 'g']
finish: ['g', '.', 'b', '.', 'g']

4. delete_before - solution

start: [ 'g', 'b', '.', '.', '.' ]
finish: [ '.', 'b', '.', '.', '.' ]

start: [ 'g', 'b', 'b', '.', 'b' ]
finish: [ '.', '.', 'b', '.', 'b' ]

Day 4 Challenges -- advanced loops & conditionals

0. bleed_right - solution

start: ['.', '.', 'b', '.', '.']
finish: ['.', '.', 'b', 'b', 'b']

1. invert_colors - solution

start: ['b', 'g', 'g', 'b', 'b']
finish: ['g', 'b', 'b', 'g', 'g']

start: ['b', '.', 'g', '.', 'b']
finish: ['g', '.', 'b', '.', 'g']

2. pull_blues_right - solution

start: ['b', '.', 'b', '.', '.']
finish: ['.', '.', '.', 'b', 'b']

3. pull_blues_left - solution

start: ['b', 'g', 'g', 'b', 'b']
finish: ['b', 'b', 'b', 'g', 'g']

4. reverse_row - solution

start: ['b', 'g', 'g', '.', 'g']
finish: ['g', '.', 'g', 'g', 'b']