Logic Masters Deutschland e.V.

In this ambiguous puzzle, clues are either U-Bahn or tetromino, based on the shapes similarities. The difficulty should land somewhere between 4 and 5/5.
In order to have a smoother experience in this puzzle, my advice as for notations would be to use numbers coding line shapes (turn=1, ...) to keep track of cells options, and to cross/shade clues that are no longer helpful.
Many thanks to Agent, Fjam, Wisty, Bells, The Cogito, filuta for testing, feedback and help phrasing the rules.
Have fun!

Rules :

Draw a line network through the centers of some cells, which may branch or turn, but may not have any dead ends.

Place some tetrominoes in the grid such that all tetromino cells form one orthogonally connected area and no 2x2 is completely filled with tetromino cells. Two tetrominoes of the same shape may not touch, not even diagonally, counting rotations and reflections as the same.

Clues outside the grid indicate either:

• the number of times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the respective row/column, irrespective of the line shape's rotation.
• the number of cells belonging to the corresponding tetromino shape in the respective row/column, where S=cross, T=branch, I=straight line and L=turn.

All tetrominoes must contain each line shape once, and all edges between cells in the same tetromino must be crossed by line segments.


For example, the 5 clue indicates that in row 5, there are five U-Bahn crosses, five cells belonging to S-tetrominoes, or both.