Instructions

Ripple Effect was first published in Puzzle Communication Nikoli in May 1998 [1]. In these puzzles, a grid is divided into polyomino-shaped rooms.

1. Each room contains consecutive numbers starting from 1. Thus, a domino will always have 1 and 2. A triomino will always have 1, 2, and 3. And so on.

2. If a number is duplicated in a row or a column, the space between the duplicated numbers must be equal to or larger than the value of the number. Thus, there will always be at least one digit between 1s, at least two digits between 2s, and so on.

Here is a solved example puzzle. The first grid is the puzzle itself. In the second, some preliminary logic has been done. To start, all single squares need a 1. Ones cannot be adjacent, which forces a few more placements. The square marked "A" cannot be a 2, since the domino above it could not be filled. With further logic, the entire puzzle is solved.