# Easy As LITS: Lots of "S"s

This is an Easy as LITS puzzle (LITS variation), where you shade cells to form tetrominoes

Rules taken from Grandmaster Puzzles:

• Shade exactly four connected cells in each outlined region, to form an L, I, T, or S tetromino.
• All shaded cells are connected with each other.
• No 2×2 group of cells can be entirely shaded black.
• When two tetrominoes in adjacent regions share an edge, they must not be of the same type (L, I, T, or S), regardless of rotations or reflections.
• The letters outside the grid indicate the first tetromino encountered in the corresponding direction.

An example puzzle and its solution, taken from Grandmaster Puzzles (who in turn credit Chris Green):

Now, solve this puzzle:

Note: if you want to solve this on the image, clickthrough to get the full size version

First answer with a fully-explained logical solution path gets the checkmark.

First, a few regions can be assigned shapes:

S must go in all three of the top regions.

And then L must go in the right region.

Now, the break-in:

Where is the L seen by column 3?
It can be either in the center region, the left region, or the bottom left. If in the bottom left, we can't satisfy the S; if in the left, then we can't connect to the top left S. So it must be in the center.

And now we can resolve most of the grid:

Note that the S in the top right can't connect left. This means it must go down and around. And in each of the regions, there's only one way we can place a piece to extend the shaded cells.

And with some connectivity arguments, the puzzle is solved:

The left region cannot connect the bottom to the top; it would have to use an L, and then there's no way we could attach the L in the middle region.
So the top-left region must go down and to the right, which places the L; finally, a T in the left region finishes off the puzzle.