Color Configuration 3x3 board

Question

I came across this question in FB. I tried to solve but unable to get the answer for it. Feeling so demotivated. This is the question:

I need to turn the whole board WHITE.
Rules of the game:
1.When you select a square, the color of that square switches (from Black to White or vice-versa).
2.In the same move, the colors of the squares at the TOP, LEFT, RIGHT, BOTTOM of the selected square, if available on the board, switch (from Black to White or vice-versa) as well. Which squares should I select to win the game.

Are you sure that question doesn't say to turn all the written numbers white.. :D — manshu, Mar 13 '16 at 16:03
It says to turn the board white! It should be covered full of white — Born2Code, Mar 13 '16 at 16:28

score 12 · Accepted Answer · answered Mar 13 '16 at 16:11

This kind of puzzle is commonly referred to as "lights out", after a board game by that name. I googled that phrase and came upon a solver at http://www.ueda.info.waseda.ac.jp/~n-kato/lightsout/. So I can't take credit for the answer but it's pretty simple:

1, 3, 7, 9

score 1 · Answer 2 · answered Mar 15 '16 at 11:27

1

The answer to that puzzle is the following moves:

First select the square number 5 to turn all the board to black.
Then select all the squares positionned in a corner which are 1, 3, 7 and 9. We obtain like that the inverse of the initial board.
Then simply select the square number 5 and all the board is white.

answered Mar 15 '16 at 11:27

thetical

11
2

2

But the 5 in step 1 and 3 cancel eachother out, so you don't need to select 5 in this set up. – Klyzx Mar 15 '16 at 16:30

Color Configuration 3x3 board

2 Answers2