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 solving puzzles called Nonograms. You can try a simple online Picross clone here: TylerK's Picross.
Nonograms are a grid, with sequences of numbers defined for every row and column of the grid. The numbers define blocks of "filled in" squares for that row/column, but the unfilled areas on either sides of the blocks are not defined. For example, if you have a row that looks like this:
(source: steam-punk.net)
Possible solutions for that row would include:
(source: steam-punk.net)
(source: steam-punk.net)
etc.
The "4 5" simply tells you that, somewhere in the row, there are 4 sequential blocks filled in, followed by 5 sequential blocks filled in. Those will be the only blocks filled in, and the amount of space before/after them are not defined.
A puzzle is complete when all rows and columns meet their definitions, without any contradictions.
Ex