Locate some "clouds" in the grid. A cloud is a rectangular-shaped (possibly square) group of cells; each cloud must have a height of at least two cells and a width of at least two cells. Clouds do not touch each other, not even diagonally (that is, if two cloud pieces are in adjacent cells, they must be part of the same cloud). The contents of some cells are given for you.
Each number to the left and top of the grid reveals the number of cloud pieces that must be located in that row or column (including any that might be given for you).
(Rules and example from PGP IB)
History of the puzzle
Appearances in the past WPCs
- WPC 2018/Round 2 by Jan Zvěřina
- WPC 2018/Individual Playoffs (unused) by Jiři Hrdina
- WPC 2015/Round 2
- WPC 2013/Part 2
- WPC 2013/Final
- WPC 2011/Part 4 ("Borderless")
- WPC 2011/Part 7