# Questions tagged [lights-out]

A type of puzzle typically involving a grid of lights, in which the challenge is to get them all to the same state (on or off). The trick is that each light also affects a number of its neighbors, with sides and corners affecting fewer.

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### Board with all 2020s

Zeroes are written in all cells of a $5 \times 5$ board. We can take an arbitrary cell and increase by 1 the number in this cell and all cells having a common side with it. Is it possible to obtain ...
2answers
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### Turn on all squares

Take a square grid of size $a\times b$, with all squares being off. You can tap a square, to reverse the state of that square and all squares located in the same column and row as the tapped square. ...
2answers
443 views

### Different numbers in all cells of a 3x3 board

This puzzle is inspired by this one: Board with all 2020s Zeroes are written in all cells of a 3×3 board. Pressing a cell increases by 1 the number in this cell and all cells having a common side with ...
2answers
322 views

### Putting up the lights two

I hope you are familiar with this. Basically Each strand of 20 lights is wired like a 5x4 grid, and each bulb can be either blue, red, purple, or green. However, when you change the color of 1 ...
1answer
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### Putting up the lights

Feeling festive, you decide it's time to put up the lights. You dig out the box and plug a strand in. Uh oh, they are all the same color. This won't work, these are supposed to be multiple colors ...
6answers
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### Counter Flipping

A counter flip game is played in the following way: In each move, you can flip an entire row or column Flipping a row or column inverts all the counters on that row or column from $X$ to $O$ or vice ...