Also known as:
Hitorinishitekure, Let Me Alone, Zahlen Streichen
Another Japanese puzzle, based on the idea of eliminating numbers according to specific rules. This puzzle appeared first in a Nikoli publication in 1990. The full name is Hitori-ni-shite-kure, 'leave me alone'.
Some of the best solving strategies are summarised, below:
All the squares contain digits. Black out certain digits in such a way that no digit appears more than once in a row or column. Blacked-out squares must not touch, either horizontally or vertically, and all remaining cells must be part of a single, unbroken area.
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