Rules and how to solve Akari.
Rules
  1. Set each cell as a white cell or a black cell to meet the following conditions.
  2. The number specified in the problem specifies the number of white cells that are continuous vertically and horizontally from this cell. The continuation of the white cell ends at the end of the frame or at the black cell.
  3. The next, upper, lower, left, and right sides of the black cell are white cells.
  4. Diagonally connected black cells do not separate the board. (All white cells are connected by top, bottom, left and right white cells.)


jump to Akari problem.

Tips for solving
解くポイントは、ある枡が黒になるとその上下左右の枡は白枡になるわけですが、この結果問題数字で指定された数を超えてしまうとすると最初の黒枡指定がおかしかったことになりますのでこの枡は白枡です。この例として②と指定された問題枡の肩の位置(たとえば右上)の枡は白枡になります。
またある枡を白枡にしないと問題で指定された白枡数にならない枡は白枡になります。この例として9×9枡の問題で左上隅に⑪という問題数字指定されていれば、左端の列の上から三つの枡と上端行の左から三つの枡は白枡になります。
このようなところから注目していきます。

それでは例題で説明します。
The point to be solved is that when a certain cell becomes black, the upper, lower, left and right cells become white cells, but if the number of white cells exceeds the number specified by the problem number, the first black cell specification was incorrect. So this is a white cell. In this example, the cell at the shoulder position (for example, upper right) of the problem cell specified as ② is a white cell.
Also, if you do not make a certain cell a white cell, the cell that does not reach the number of white cells specified in the question will be a white cell.As an example, if the problem number is designated as “⑪” in the upper left corner in a 9 × 9 cells problem, the three cells from the top of the left column and the three cells from the left of the top row are white cells.
Let's pay attention from such a place.
Let me explain with an example.
The following figure is the problem. Pay attention to the problem cell ② in the upper left. ex0
First, pay attention to the yellow frame cell. If any of these yellow frames are black, two cells of the upper, lower, left, and right sides of the cell ② will become white, and the number of white cells from the cell ② will be three, exceeding the specified two.Therefore, the four squares in the yellow frame are white. In addition, if either of the green cells is a white cell, the continuation of the white cell from the cell ② will be the specified 2, so the end point of the white cell is a black cell.
Whichever green frame is white, two red frames are black, but the upper left corner is split by black. It is wrong to change the first green frame to a white one, so the two green frames must be black. The top, bottom, left, and right of the black cell are white cell.
ex1
This time, pay attention to the problem cell ⑩ at the left end. Even if the leftmost column is all white from the top to the bottom, the continuity of the white cells is only 7 so the three cells on the right side of ⑩(yellow frame) are white cells. Also, even if all of the cells in the fifth row from the top with ⑩ become white, the continuity of white cells will be 7 even if the cells under ⑩ are all white. One cell above the cell ⑩ (green frame cell) is also a white cell. ex2
This time, focus on ③ at the bottom. Assuming that one of the green frames at the position of the shoulder in step ③ is a black one, one of the yellow and red frames is a white one, and the number of consecutive white cells is 4, which exceeds the specified 3 in problem cell. Therefore, the two cells in the green frame must be white cells. ex3
Now consider again the yellow framed cell above ② in the upper left. If this cell is a white cell, the number of consecutive white cells starting from ② will be 2, so the green frame on the left of ② will be a black cell. Then, in order for the mass of the white cell in the upper left not to be divided by the black cella, the cell in the red frame must be a white cell. Since the continuation will be 5, the first yellow frame must be a black cell. If the red frame is not a white one, it will be divided by a black one, so it will be a white one. The number of white cells starting from the cell in ③ has also become 3, so the right and bottom of ③ are black cell. The top of the central ⑩ will also be a white one so that the black one will not divide board. ex4
Now look at the cell ⑤ at the right end. The green frame above this cell is a white cell so that the black cell does not divide board. If the red cell on the left is a white ,the continuos white cell number exceeds the designated number of 5, so it's a black cell. ex4
Now look at ④ in the lower right.If the green frame in the upper left of ④ is a black cell, the white cells will exceed four, so here is the white cell. If the cell in the blue frame under ④ becomes a black cell, the white cells will not be 4 even if the white cells are not determined yet, so they are also white cells. If you think in the same way, you should reach the correct solution in the lower figure. ex6
ex7 ex8



2020.2.28 Modified
2010.6.12 First edition
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