# LITS > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/LITS > Markdown URL: https://mediated.wiki/source/LITS.md > Source: https://en.wikipedia.org/wiki/LITS > Source revision: 1332757889 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Logic puzzle typically played on a 10×10 board}} [[Image:LITS.png|thumb|right|Moderately difficult ''LITS'' puzzle ([solution](/source/Media%3ALITS-solution.png))]] '''LITS''', formerly known as '''Nuruomino''' (ヌルオミノ), is a binary determination puzzle published by [Nikoli](/source/Nikoli_(publisher)).[https://web.archive.org/web/20080205125710/http://www.nikoli.co.jp/en/puzzles/lits/ Nikoli's English page on ''LITS''] ==Rules== ''LITS'' is played on a [rectangular grid](/source/Regular_grid), typically 10×10; the grid is divided into [polyomino](/source/polyomino)es, none of which have fewer than four cells. The goal is to shade in a [tetromino](/source/tetromino) within each pre-printed polyomino in such a way that no two matching tetrominoes are orthogonally adjacent (with rotations and reflections counting as matching), and that the shaded cells form a valid [nurikabe](/source/Nurikabe_(puzzle)): they are all orthogonally contiguous (form a single polyomino) and contain no 2×2 square tetrominoes as subsets. ==History== The puzzle was first printed in ''[Puzzle Communication Nikoli](/source/Puzzle_Communication_Nikoli) #106''; the original title is a combination of 'nuru' ([Japanese](/source/Japanese_language): "to paint") and 'omino' ([polyomino](/source/polyomino)). In issue #112, the title was changed to the present one, which represents the four (of five) tetrominoes used in the puzzle: the L-shape, the straight, the T-shape, and the skew (square tetrominoes may never appear in the puzzle as they are a direct violation of the rule). ==Complexity== Testing whether a given LITS puzzle has a solution is [NP-complete](/source/NP-complete).{{citation|url=https://itn-web.it.liu.se/~chrsc91/papers/norinori-lits.pdf|contribution=Computational complexity and bounds for Norinori and LITS|first1=Michael|last1=Biro|first2=Christiane|last2=Schmidt|title=EuroCG 2017, Malmö, Sweden, April 5–7, 2017}} ==See also== *[List of Nikoli puzzle types](/source/List_of_Nikoli_puzzle_types) ==References== {{reflist}} Category:Logic puzzles Category:Japanese board games {{puzzle-game-stub}} --- Adapted from the Wikipedia article [LITS](https://en.wikipedia.org/wiki/LITS) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/LITS?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.