Ripple Effect is a logic puzzle

Logic puzzle

A logic puzzle is a puzzle deriving from the mathematics field of deduction.-History:The logic puzzle was first produced by Charles Lutwidge Dodgson, who is better known under his pen name Lewis Carroll, the author of Alice's Adventures in Wonderland...

 published by Nikoli

Nikoli

Nikoli Co., Ltd. is a Japanese publisher that specializes in games and, especially, logic puzzles. Nikoli is also the nickname of a quarterly magazine issued by the company...

. As of 2007, two books consisting entirely of Ripple Effect puzzles have been published by Nikoli. The second was published on October 4, 2007.

Rules

Ripple Effect is played on a rectangular grid divided into polyomino

Polyomino

A polyomino is a plane geometric figure formed by joining one or more equal squares edge to edge. It is a polyform whose cells are squares. It may be regarded as a finite subset of the regular square tiling with a connected interior....

es. The solver must place one positive integer

Integer

The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...

 into each cell of the grid - some of which may be given in advance - according to these rules:

• Every polyomino must contain the consecutive integers from 1 to the quantity of cells in that polyomino inclusive.
• If two identical numbers appear in the same row or column, at least that many cells with other numbers must separate them. For example, two cells both containing '1' may not be orthogonally adjacent, but must have at least one cell between them with a different number. Two cells marked '3' in the same row or column must have at least three cells with other numbers between them in that row or column, and so on.

History

Ripple Effect is an original puzzle of Nikoli; it first appeared in Puzzle Communication Nikoli #73 (May 1998).

External links

• http://www.nikoli.co.jp/ja/puzzles/ripple_effect/