Solving Nonograms (Picross)

Question

it\'s Friday afternoon, let\'s have a fun puzzle/algorithm problem to solve.

One of my favorite Nintendo DS games is Picross DS. The game is quite simple, it involves so

Answer 1

Let me point out 2 interesting twists on the classic nonogram puzzles :

• When the puzzle does more than just list lengths of occupied cells. This public challenge constrained some cells in advance as being occupied : http://www.gchq.gov.uk/press_and_media/news_and_features/Pages/Directors-Christmas-puzzle-2015.aspx

• When the nonogram contains more than just empty/occupied cells, but uses patches of different colors to occupy the cells. For example see http://onlinenonograms.com ; from solving these by hand, I get the feeling that these are actually easier to solve than the regular nonograms.

A particular challenge for algorithm designers is that the colored nonograms benefit greatly from considering horizontal/vertical constraints together. The usual line-per-line solvers are at a clear disadvantage here.