# Nia11's solution

## to Diamond in the Ruby Track

Published at Sep 07 2020 · 0 comments
Instructions
Test suite
Solution

The diamond kata takes as its input a letter, and outputs it in a diamond shape. Given a letter, it prints a diamond starting with 'A', with the supplied letter at the widest point.

## Requirements

• The first row contains one 'A'.
• The last row contains one 'A'.
• All rows, except the first and last, have exactly two identical letters.
• All rows have as many trailing spaces as leading spaces. (This might be 0).
• The diamond is horizontally symmetric.
• The diamond is vertically symmetric.
• The diamond has a square shape (width equals height).
• The letters form a diamond shape.
• The top half has the letters in ascending order.
• The bottom half has the letters in descending order.
• The four corners (containing the spaces) are triangles.

## Examples

In the following examples, spaces are indicated by characters.

Diamond for letter 'A':

A

Diamond for letter 'C':

C路路路C

Diamond for letter 'E':

E路路路路路路路E

For installation and learning resources, refer to the Ruby resources page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

gem install minitest

If you would like color output, you can require 'minitest/pride' in the test file, or note the alternative instruction, below, for running the test file.

Run the tests from the exercise directory using the following command:

ruby diamond_test.rb

To include color from the command line:

ruby -r minitest/pride diamond_test.rb

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### diamond_test.rb

require 'minitest/autorun'
require_relative 'diamond'

class DiamondTest < Minitest::Test
def test_letter_a
end

def test_letter_c
skip
string = "  A  \n"\
" B B \n"\
"C   C\n"\
" B B \n"\
"  A  \n"
end

def test_letter_e
skip
string = "    A    \n"\
"   B B   \n"\
"  C   C  \n"\
" D     D \n"\
"E       E\n"\
" D     D \n"\
"  C   C  \n"\
"   B B   \n"\
"    A    \n"
end
end
module Diamond
ALPHA = '0ABCDEFGHIJKLMNOPQRSTUVWXYZ'
def self.make_diamond(letter)
index = ALPHA.index(letter)
d = []
(1..index).each{ |i|
line = " " * (2 * index)
line[index + 1 - i] = ALPHA[i]
line[index - 1 + i] = ALPHA[i]
line[0] = ''
d.push(line + "\n")
}
d += d[0...-1].reverse
d.join
end
end

### What can you learn from this solution?

A huge amount can be learned from reading other people鈥檚 code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

• What compromises have been made?
• Are there new concepts here that you could read more about to improve your understanding?