Shade some empty cells so that shaded sections form squares and a number in a cell indicates the total of the areas of the squares touching that cell by a side. All white cells must form a single connected area. Cells with numbers remain white.
(Rules and example from WPC 2017 IB)
History of the puzzle
First appeared on Nikoli volume 123 (2008). Invented by あるかり工場長 (Alkali Kojocho). Mochikoro comes from "mochi" + "colony" in Japanese.
Appearances in the past WPCs
- WPC 2017/Round 7 by Prasanna Seshadri