Locate some tetrominoes in the grid. Each piece of a tetromino occupies a single cell. Tetrominoes do not touch each other, not even diagonally (that is, if two tetromino pieces are in adjacent cells, they must be part of the same tetromino). The same tetromino cannot appear more than once. Two tetrominoes are considered the same if one can be rotated to match the other. (Reflections are considered different.)
Some numbers are given at corners of the grid, which must match the number of cells touching that corner that are part of a tetromino.
(Rules and example from PGP IB)
- Just like Pentominoes puzzle, the set of polyominoes used in this puzzle is not confined to tetrominoes; any arbitrary set theoretically works.
- Instead of placing some of the polyominoes from the set, some rules require to place all polyominoes from the set.
History of the puzzle
Invented by Serkan Yürekli (Turkey). First appeared on the 8th 24-Hour Puzzle Championship (2007).
Appearances in the past WPCs
- WPC 2016/Round 2 by Matej Uher