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JaeHyoLee's solution

to Minesweeper in the Lua Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Add the numbers to a minesweeper board.

Minesweeper is a popular game where the user has to find the mines using numeric hints that indicate how many mines are directly adjacent (horizontally, vertically, diagonally) to a square.

In this exercise you have to create some code that counts the number of mines adjacent to a square and transforms boards like this (where * indicates a mine):

+-----+
| * * |
|  *  |
|  *  |
|     |
+-----+

into this:

+-----+
|1*3*1|
|13*31|
| 2*2 |
| 111 |
+-----+

Running the tests

To run the tests, run the command busted from within the exercise directory.

Further information

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.

Submitting Incomplete Solutions

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

minesweeper_spec.lua

local minesweeper = require('minesweeper')

describe('minesweeper', function()
  it('should be able to transform a 1x1 board with a single mine', function()
    local input = {
      '*-*',
      '|*|',
      '*-*'
    }
    local expected = {
      '*-*',
      '|*|',
      '*-*'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should be able to transform a board with no mines', function()
    local input = {
      '*---*',
      '|   |',
      '|   |',
      '|   |',
      '*---*'
    }
    local expected = {
      '*---*',
      '|   |',
      '|   |',
      '|   |',
      '*---*'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should be able to transform a small board with a single mine', function()
    local input = {
      '*---*',
      '|   |',
      '| * |',
      '|   |',
      '*---*'
    }
    local expected = {
      '*---*',
      '|111|',
      '|1*1|',
      '|111|',
      '*---*'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should be able to transform a small board with multiple mines', function()
    local input = {
      '*---*',
      '|   |',
      '|** |',
      '|   |',
      '*---*'
    }
    local expected = {
      '*---*',
      '|221|',
      '|**1|',
      '|221|',
      '*---*'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should be able to transform a larger board with multiple mines', function()
    local input = {
      '+------+',
      '| *  * |',
      '|  *   |',
      '|    * |',
      '|   * *|',
      '| *  * |',
      '|      |',
      '+------+'
    }
    local expected = {
      '+------+',
      '|1*22*1|',
      '|12*322|',
      '| 123*2|',
      '|112*4*|',
      '|1*22*2|',
      '|111111|',
      '+------+'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should be able to transform a board that is not square', function()
    local input = {
      '*---*',
      '|   |',
      '|** |',
      '*---*'
    }
    local expected = {
      '*---*',
      '|221|',
      '|**1|',
      '*---*'
    }
    assert.same(expected, minesweeper.transform(input))
  end)

  it('should assert that the board is a rectangle', function()
    local input = {
      '*---*',
      '|  |',
      '| * |',
      '*---*'
    }
    assert.has_error(function()
      minesweeper.transform(input)
    end)
  end)

  it('should assert that the input contains only space and asterisk characters on the board', function()
    local input = {
      '*---*',
      '|   |',
      '| X |',
      '*---*'
    }
    assert.has_error(function()
      minesweeper.transform(input)
    end)
  end)
end)
local function increase_element(e)
  if e == ' ' then e = 1
  elseif nil ~= tonumber(e) then e = tonumber(e) + 1 end
  return e
end

local function increase_neighbors(prevRow, currentRow, nextRow, j)
  prevRow[j-1] = increase_element(prevRow[j-1])
  prevRow[j] = increase_element(prevRow[j])
  prevRow[j+1] = increase_element(prevRow[j+1])

  currentRow[j-1] = increase_element(currentRow[j-1])
  currentRow[j+1] = increase_element(currentRow[j+1])

  nextRow[j-1] = increase_element(nextRow[j-1])
  nextRow[j] = increase_element(nextRow[j])
  nextRow[j+1] = increase_element(nextRow[j+1])
end

local function transform(input)

  local output = {}
  local width = #input[1]

  for i= 2, #input-1 do
    if width ~= #input[i] then assert(false, 'wrong!') end

    local prevRow = {}
    local currentRow = {}
    local nextRow = {}

    for w in string.gmatch(output[i-1] or input[i-1], '.') do table.insert(prevRow, w) end
    for w in string.gmatch(output[i] or input[i], '.') do table.insert(currentRow, w) end
    for w in string.gmatch(output[i+1] or input[i+1], '.') do table.insert(nextRow, w) end

    for j = 2, width - 1 do
      if currentRow[j] == '*' then increase_neighbors(prevRow, currentRow, nextRow, j)
      elseif currentRow[j] ~= ' ' and tonumber(currentRow[j]) == nil then assert(false, 'wrong character!') end
    end
    output[i-1] = table.concat(prevRow)
    output[i] = table.concat(currentRow)
    output[i+1] = table.concat(nextRow)
  end
  return output
end

return {
  transform = transform
}

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