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.
In the following examples, spaces are indicated by 路
characters.
Diamond for letter 'A':
A
Diamond for letter 'C':
路路A路路
路B路B路
C路路路C
路B路B路
路路A路路
Diamond for letter 'E':
路路路路A路路路路
路路路B路B路路路
路路C路路路C路路
路D路路路路路D路
E路路路路路路路E
路D路路路路路D路
路路C路路路C路路
路路路B路B路路路
路路路路A路路路路
To run the tests, run the command busted
from within the exercise directory.
For more detailed information about the Lua track, including how to get help if you're having trouble, please visit the exercism.io Lua language page.
Seb Rose http://claysnow.co.uk/recycling-tests-in-tdd/
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
local diamond = require 'diamond'
describe('diamond', function()
it('should generate the diamond for A', function()
assert.are.equal('A\n', diamond('A'))
end)
it('should generate the diamond for B', function()
local expected =
' A \n' ..
'B B\n' ..
' A \n'
assert.are.equal(expected, diamond('B'))
end)
it('should generate the diamond for C', function()
local expected =
' A \n' ..
' B B \n' ..
'C C\n' ..
' B B \n' ..
' A \n'
assert.are.equal(expected, diamond('C'))
end)
it('should generate the diamond for E', function()
local expected =
' 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'
assert.are.equal(expected, diamond('E'))
end)
it('should generate the diamond for H', function()
local expected =
' A \n' ..
' B B \n' ..
' C C \n' ..
' D D \n' ..
' E E \n' ..
' F F \n' ..
' G G \n' ..
'H H\n' ..
' G G \n' ..
' F F \n' ..
' E E \n' ..
' D D \n' ..
' C C \n' ..
' B B \n' ..
' A \n'
assert.are.equal(expected, diamond('H'))
end)
end)
return function(seed)
local start = 'A'
local max = seed:byte()
local min = start:byte()
local diff = max - min
if diff == 0 then
return 'A\n'
end
local diamond = seed .. (' '):rep(diff - 1).. ' ' .. (' '):rep(diff - 1) .. seed .. '\n'
for index=max - 1, min + 1, -1 do
local c = string.char(index)
local line = (' '):rep(max - index) .. c .. (' '):rep(index - min)
line = line .. string.rep(' ', index - min - 1) .. c .. string.rep(' ', max - index) .. '\n'
diamond = line .. diamond .. line
end
local first_line = (' '):rep(diff) .. start .. (' '):rep(diff) .. '\n'
diamond = first_line .. diamond .. first_line
return diamond
end
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