Nurikabe Solver
Solve a Nurikabe puzzle by shading the sea around its islands.
Nurikabe, also called Islands in the Stream, asks you to shade some cells black to make a sea. Each numbered cell belongs to a white island of exactly that many cells, islands never touch each other orthogonally, all of the black sea is connected, and the sea never contains a 2 by 2 block. Type a number into each clue cell, leaving the rest blank, then solve.
Enter an island size, or leave a cell blank.
How it works
The solver places one island at a time, trying every connected shape of the clue's size that contains its number and never touches another island. Whatever cells are left over become the sea, which it then checks for a single connected region with no 2 by 2 block.
A proper Nurikabe has one solution; the solver reports when more than one shading fits.