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Rules (taken from Nikoli):

  1. Place light bulbs (circles) according to the following rules.
  2. Light bulbs may be placed in any of the white squares, the number in the square shows how many light bulbs are next to it, vertically and horizontally.
  3. Each light bulb illuminates from bulb to black square or outer frame in its row and column.
  4. Every white square must be illuminated and a light bulb can not illuminate another light bulb.

Adding note for avoiding the duplicate error with Akari: The Light.


2 Answers 2


Final solution

final solution

Step by step deduction

Some "easy" deductions (no lights around 0, lights in white squares surrounded by black, etc.) get us to here:

first steps

See that 1 in the fourth row, third column? I'm going to assume the light next to it is on the right, and then we can deduce as follows to get a contradiction:

first contradiction

In fact, that same contradiction would arise just from saying there is no light between the two 1s in the ninth row (then there must be a light below the left one, to the right of the right one, and around the 2 below that). So we have:

next steps

Now in the right-hand column, the square just above the bottom 1 can only be lit from one possible place. From there we get lots more deductions, finishing off the bottom half of the board:

almost done

See those two 1s almost next to each other near the top of the eighth column? If they have no light between them, then we get a contradiction as follows:

second contradiction

So they must have a light between them, and we finish off the board as follows:

final solution

  • $\begingroup$ Just pwned me :P $\endgroup$
    – ABcDexter
    Mar 28, 2020 at 11:59
  • $\begingroup$ I'm accepting this answer as this provides explanations despite it's beaten by several minutes. Great job and +1 for both of you :) $\endgroup$
    – athin
    Mar 28, 2020 at 21:53

Here is the solution:

(Red means light bulb, yellow means light)

Akari Puzzle: Solution

  • $\begingroup$ Beat me by some minutes :-) +1 $\endgroup$ Mar 28, 2020 at 11:56

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