Unruly Unruly
Elementary+
English

This mission is an adaptation of the "Unruly" game (from Simon Tatham's Portable Puzzle Collection). If you are lost or just want to play, the game is available here.

You have an uncompleted rectangular grid and have to colour all the cells, either black or white, with two constraints:

  • No three consecutives cells, horizontally or vertically, are all black or all white.
  • Each row and column contains as many black cells as white cells.
Obviously, you can only change the empty cells, not the colored ones.

The grid will be represented by a tuple of strings. Empty cells are represented by '.', black cells by 'B' and white cells by 'W'.

6x6 example image

('......',          ('BBWWBW',
 '..B...',           'BWBWBW',
 'W.B.W.',           'WWBBWB',
 '......',           'BBWWBW',
 'W...W.',           'WBWBWB',
 'WW..W.')           'WWBBWB')

Input: A tuple of strings.

Output: A tuple/list/iterable of strings.

Example:

unruly(('......',
        '..B...',
        'W.B.W.',
        '......',
        'W...W.',
        'WW..W.')) == ('BBWWBW',
                       'BWBWBW',
                       'WWBBWB',
                       'BBWWBW',
                       'WBWBWB',
                       'WWBBWB')

Preconditions:

  • Given puzzles are solvable.
  • You can solve all puzzles without making any guesses.
  • 6 ≤ len(grid) ≤ 40 and 6 ≤ len(grid[0]) ≤ 30.
  • all(len(row) == len(grid[0]) for row in grid).