# Rollercoaster

*Not to be confused with "Roller Coaster", a puzzle that appeared in MIT Puzzle Hunt and GM Puzzles blog. See Labyrinth.*

## Rules edit

Place the digits from 1 to N exactly once each into every row and column. Every digit should be either greater or smaller than all its adjacent neighbours.

(Rules (modified) and example (N=8) from WPC 2015 IB)

### Rule variations edit

- In WPC 2015 puzzles, N had a fixed value of 8. Theoretically, N can take any value, though it probably cannot be an odd number. (Not a proven fact)

## History of the puzzle edit

Its first appearance is currently unknown but earlier than 2009 Belarus Nationals, where it appeared under the name "Супер 8" (translated as Super 8).

## Appearances in the past WPCs edit

- WPC 2015/Round 3 by Vladimir Portugalov