# paulfioravanti's solution

## to Diamond in the Ruby Track

Published at May 20 2019 · 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':

``````··A··
·B·B·
C···C
·B·B·
··A··
``````

Diamond for letter 'E':

``````····A····
···B·B···
··C···C··
·D·····D·
E·······E
·D·····D·
··C···C··
···B·B···
····A····
``````

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``````
``````# frozen_string_literal: true

module Diamond
DIAMOND_TIP = "A"
private_constant :DIAMOND_TIP
NEWLINE = "\n"
private_constant :NEWLINE
SPACE = " "
private_constant :SPACE

module_function

def make_diamond(max_letter)
letters = generate_letters(max_letter)

letters
.each
.join
end

def generate_letters(max_letter)
(DIAMOND_TIP..max_letter).to_a + (DIAMOND_TIP...max_letter).to_a.reverse
end
private_class_method :generate_letters

def length_from_center(letter)
letter.ord - DIAMOND_TIP.ord
end
private_class_method :length_from_center

line =
if letter == DIAMOND_TIP
diamond_tip(letter, diamond_height)
else
end
acc << line + NEWLINE
end

def diamond_tip(letter, diamond_height)
letter.center(diamond_height)
end
private_class_method :diamond_tip

# Pad string spacing outwards from center first, then have outer
# padding fill in the remaining gaps, if any.
half_row =
letter

half_row + SPACE + half_row.reverse
end
private_class_method :diamond_row
end``````