Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.
To begin with, convert a simple binary font to a string containing 0 or 1.
The binary font uses pipes and underscores, four rows high and three columns wide.
_ #
| | # zero.
|_| #
# the fourth row is always blank
Is converted to "0"
#
| # one.
| #
# (blank fourth row)
Is converted to "1"
If the input is the correct size, but not recognizable, your program should return '?'
If the input is the incorrect size, your program should return an error.
Update your program to recognize multi-character binary strings, replacing garbled numbers with ?
Update your program to recognize all numbers 0 through 9, both individually and as part of a larger string.
_
_|
|_
Is converted to "2"
_ _ _ _ _ _ _ _ #
| _| _||_||_ |_ ||_||_|| | # decimal numbers.
||_ _| | _||_| ||_| _||_| #
# fourth line is always blank
Is converted to "1234567890"
Update your program to handle multiple numbers, one per line. When converting several lines, join the lines with commas.
_ _
| _| _|
||_ _|
_ _
|_||_ |_
| _||_|
_ _ _
||_||_|
||_| _|
Is converted to "123,456,789"
Execute the tests with:
$ elixir ocr_numbers_test.exs
In the test suites, all but the first test have been skipped.
Once you get a test passing, you can unskip the next one by
commenting out the relevant @tag :pending
with a #
symbol.
For example:
# @tag :pending
test "shouting" do
assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end
Or, you can enable all the tests by commenting out the
ExUnit.configure
line in the test suite.
# ExUnit.configure exclude: :pending, trace: true
For more detailed information about the Elixir track, please see the help page.
Inspired by the Bank OCR kata http://codingdojo.org/cgi-bin/wiki.pl?KataBankOCR
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
if !System.get_env("EXERCISM_TEST_EXAMPLES") do
Code.load_file("ocr_numbers.exs", __DIR__)
end
ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)
defmodule OCRNumbersTest do
use ExUnit.Case
# @tag :pending
test "Recognizes 0" do
number =
OCRNumbers.convert([
" _ ",
"| |",
"|_|",
" "
])
assert number == {:ok, "0"}
end
@tag :pending
test "Recognizes 1" do
number =
OCRNumbers.convert([
" ",
" |",
" |",
" "
])
assert number == {:ok, "1"}
end
@tag :pending
test "Unreadable but correctly sized inputs return ?" do
number =
OCRNumbers.convert([
" ",
" _",
" |",
" "
])
assert number == {:ok, "?"}
end
@tag :pending
test "Input with a number of lines that is not a multiple of four raises an error" do
number =
OCRNumbers.convert([
" _ ",
"| |",
" "
])
assert number == {:error, 'invalid line count'}
end
@tag :pending
test "Input with a number of columns that is not a multiple of three raises an error" do
number =
OCRNumbers.convert([
" ",
" |",
" |",
" "
])
assert number == {:error, 'invalid column count'}
end
@tag :pending
test "Recognizes 110101100" do
number =
OCRNumbers.convert([
" _ _ _ _ ",
" | || | || | | || || |",
" | ||_| ||_| | ||_||_|",
" "
])
assert number == {:ok, "110101100"}
end
@tag :pending
test "Garbled numbers in a string are replaced with ?" do
number =
OCRNumbers.convert([
" _ _ _ ",
" | || | || | || || |",
" | | _| ||_| | ||_||_|",
" "
])
assert number == {:ok, "11?10?1?0"}
end
@tag :pending
test "Recognizes 2" do
number =
OCRNumbers.convert([
" _ ",
" _|",
"|_ ",
" "
])
assert number == {:ok, "2"}
end
@tag :pending
test "Recognizes 3" do
number =
OCRNumbers.convert([
" _ ",
" _|",
" _|",
" "
])
assert number == {:ok, "3"}
end
@tag :pending
test "Recognizes 4" do
number =
OCRNumbers.convert([
" ",
"|_|",
" |",
" "
])
assert number == {:ok, "4"}
end
@tag :pending
test "Recognizes 5" do
number =
OCRNumbers.convert([
" _ ",
"|_ ",
" _|",
" "
])
assert number == {:ok, "5"}
end
@tag :pending
test "Recognizes 6" do
number =
OCRNumbers.convert([
" _ ",
"|_ ",
"|_|",
" "
])
assert number == {:ok, "6"}
end
@tag :pending
test "Regonizes 7" do
number =
OCRNumbers.convert([
" _ ",
" |",
" |",
" "
])
assert number == {:ok, "7"}
end
@tag :pending
test "Recognizes 8" do
number =
OCRNumbers.convert([
" _ ",
"|_|",
"|_|",
" "
])
assert number == {:ok, "8"}
end
@tag :pending
test "Recognizes 9" do
number =
OCRNumbers.convert([
" _ ",
"|_|",
" _|",
" "
])
assert number == {:ok, "9"}
end
@tag :pending
test "Recognizes string of decimal numbers" do
number =
OCRNumbers.convert([
" _ _ _ _ _ _ _ _ ",
" | _| _||_||_ |_ ||_||_|| |",
" ||_ _| | _||_| ||_| _||_|",
" "
])
assert number == {:ok, "1234567890"}
end
@tag :pending
test "Numbers separated by empty lines are recognized. Lines are joined by commas." do
number =
OCRNumbers.convert([
" _ _ ",
" | _| _|",
" ||_ _|",
" ",
" _ _ ",
"|_||_ |_ ",
" | _||_|",
" ",
" _ _ _ ",
" ||_||_|",
" ||_| _|",
" "
])
assert number == {:ok, "123,456,789"}
end
end
defmodule OCRNumbers do
@doc """
Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or
whether it is garbled.
"""
@spec convert([String.t]) :: String.t
def convert([
" _ ",
"| |",
"|_|",
" ",
]), do: {:ok, "0"}
def convert([
" ",
" |",
" |",
" ",
]), do: {:ok, "1"}
def convert([
" _ ",
" _|",
"|_ ",
" ",
]), do: {:ok, "2"}
def convert([
" _ ",
" _|",
" _|",
" ",
]), do: {:ok, "3"}
def convert([
" ",
"|_|",
" |",
" ",
]), do: {:ok, "4"}
def convert([
" _ ",
"|_ ",
" _|",
" ",
]), do: {:ok, "5"}
def convert([
" _ ",
"|_ ",
"|_|",
" ",
]), do: {:ok, "6"}
def convert([
" _ ",
" |",
" |",
" ",
]), do: {:ok, "7"}
def convert([
" _ ",
"|_|",
"|_|",
" ",
]), do: {:ok, "8"}
def convert([
" _ ",
"|_|",
" _|",
" ",
]), do: {:ok, "9"}
def convert([
<<_ :: bytes-size(3)>>,
<<_ :: bytes-size(3)>>,
<<_ :: bytes-size(3)>>,
<<_ :: bytes-size(3)>>,
]), do: {:ok, "?"}
def convert([
<<l1h :: bytes-size(3), l1t :: binary>>,
<<l2h :: bytes-size(3), l2t :: binary>>,
<<l3h :: bytes-size(3), l3t :: binary>>,
<<l4h :: bytes-size(3), l4t :: binary>>,
]) do
case convert([l1t, l2t, l3t, l4t]) do
{:error, error} -> {:error, error}
{:ok, tail_result} ->
case convert([l1h, l2h, l3h, l4h]) do
{:error, error} -> {:error, error}
{:ok, head_result} -> {:ok, "#{head_result}#{tail_result}"}
end
end
end
def convert([_, _, _, _]), do: {:error, 'invalid column count'}
def convert([l1, l2, l3, l4 | tail]) do
case convert(tail) do
{:error, error} -> {:error, error}
{:ok, tail_result} ->
case convert([l1, l2, l3, l4]) do
{:error, error} -> {:error, error}
{:ok, head_result} -> {:ok, "#{head_result},#{tail_result}"}
end
end
end
def convert(_), do: {:error, 'invalid line count'}
end
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