Place a number from 1 to X (integers only) into each cell so that each number appears exactly once in each row and column. (X is the number of cells in each row.) Each number represents a skyscraper of its respective height. The numbers outside the grid indicate how many skyscrapers can be seen in the respective row or column from the respective direction; smaller skyscrapers are hidden behind higher ones.
(Rules and example from PGP IB)
History of the puzzle
Invented by Masanori Natsuhara (Japan) in 1992 on the Puzzler magazine. Originally entitled "ビルディングシティパズル" (Building City Puzzle).
Appearances in the past WPCs
- WPC 2019/Round 2 (Classic, Mixed Information) by Gabi Penn-Karras
- WPC 2019/Round 4 (Doppelblock Skyscrapers) by Roland Voigt
- WPC 2019/Round 5 (Skyscraper Cluster) by Christian Halberstadt
- WPC 2019/Round 9 by Ulrich Voigt
- WPC 2019/Team Playoffs (Doppelblock + Skyscrapers Sums) by Rainer Biegler
- WPC 2019/World Cup Playoffs by Roland Voigt
- WPC 2018/Round 2 (A Skyscrapers variant round) by Jiří Hrdina
- WPC 2018/Round 4 (Hexagonal) by František Luskač
- WPC 2018/Round 4 (Pyramidal, part of a combination puzzle) by Jiří Hrdina