Rules and how to solve Norinori.
Rules
  1. Put two black cells on a group of cell enclosed by thick lines. The remaining cell is a white cell.
  2. All the black cells on the board are arranged vertically or horizontally. There must not be only one or more than two clumps.

Tips for solving
解くポイントはまず二枡のグループを探します。ここはどちらの枡も黒枡に決まります。二桝並んだ黒枡が決まったらその上下左右の枡は黒枡には出来ませんので白桝のマークをしておくと良いでしょう。
まだ黒枡が一つもないグループでも白黒決まっていない枡が二つしか残っていなければその二桝は黒枡になりますし、 白黒決まってない枡が残り一つでそのグループに入れる黒枡の残りが一つなら残り一つの枡も黒枡になります。
白黒決まっていない一桝の上下左右の隣枡が白桝になるならその枡は白桝になります。
黒枡が決まったあとその上下左右で黒枡にできる枡が一つならそこを黒枡にして二桝の黒枡の塊にします。
近くに黒枡に決まっている一つの枡が二か所以上ある時は それぞれの枡が黒枡2枡になった時繋がって3枡以上の黒枡の塊にならないように注意します。
それでは例題で説明します。
以下の説明では白黒決定の手順がはっきりするよう未定の枡は灰色で表示しています。実際のパズルでは黒枡以外はすべて白枡として扱っています。
The point to solve is to first find a group of two cells. Here, both cell is determined to be a black cell. Once the two black cells are lined up, the upper, lower, left and right cells cannot be black, so it is better to mark them as white cells.
If there are only two cells which are not decided black or white left in a group with no black cell yet, the two cells will be black cells. and if there are only one cell which are not decided black or white left in a group with one black cell yet, the remained cell will be black cell.
If the top, bottom, left and right neighbors of an undetermined black cell and white cell are white cells, the center cell is a white cell.
After the black cell is decided, if there is one cell that can be made into black cell at the top, bottom, left and right neighbors, it is made into a black cell and it is made into two block of black cell.
When there is more than one place that is determined to be a black cell nearby, and when each cell becomes two black cell, be careful not to connect them to form a mass of three or more black cell.

Let me explain with an example. In the following explanation, undetermined cells are shown in gray to make the procedure for determining black and white clear. In the actual puzzle, everything except black cell is treated as white cell.
The following figure is the problem.The thick line is the group border.
First, find a group of two cells, and make them two black cells.
ex0
When two cells of black are formed in a row, the top, bottom, left and right neighbors are white.
If you look at the group of three cells at the bottom left, one of the cells is a white, so the remaining two cellss in the blue frame are black.
In addition, since the top, bottom, left, and right of the square with a yellow-green frame are white, even if this cell is a black cell, it cannot be made into a block of two black cell, so it will be a white cell.
ex1
Next, let's consider the group of cells on the left. In this group, the cells which are undecided to black or white are two with yellow-green framed, and there is no black cell, so the yellow-green framed cells are black cells. ex2
Next, the black cell in the light blue frame on the left can be extended only to the light blue frame above them, so both the cells in the light blue frame will be black cell.
On the other hand, since the black cell in the blue frame can be extended to the top and right, it is not possible to decide which one is the black cell here, so reserve it.
ex3
In the group of four cells on the upper left, the yellow-green frame is the second black cell in the group. Since it can be expanded only to the right, the cell in the yellow-green frame on the right side also becomes a black cell. ex4
Next, the cell with the blue frame that was reserved earlier can only be expanded to the right, so the cell with the blue frame on the right becomes a black cell. ex5
In the upper right group, the two cells, the light blue frame and the yellow-green frame, which were not determined in black and white, became black cells, The cell under the light blue frame is determined as the black cell, so the cell under the yellow-green cell is also determined as the black cell. ex6
At the end, the two cells with the blue frame are the black cells. ex7
This is the correct solution. ex8
Next, let's introduce some patterns of solving method.The diagram is for illustrative purposes and is not a solvable problem.
See the following figure. A black cell may be determined immediately next to a group of two cells.
Let's look at a group of three cells adjacent to two cells group. In the upper right, the purple cell becomes a blackcell.The L-shaped three cells under it, it is determined like light blue.
Next, in the four cells, the blue cell is determined as the black cell as shown on the left. Also, in the L-shaped four cells, if the black cell is expanded from the light blue cell to the red cell, there is no place for another black cell, so two cells in the yellow cell become black cells.
In addition, when the two sides are sandwiched between two black ones like the six left ones, the yellow-green frame in the center becomes the black one.
Until you can solve it smoothly, it is easier to find the position of the black cell if you mark the white cell firmly.
ex10
Consider the group with a light blue cell in the lower left of the following figure.This group currently has one black cell. You have to decide on another black cell, but if one of the light blue cell is a black cell, the next cell in the other group must also be a black cell. The only cell that can be expanded to other groups is the cell with the blue frame, so the cell with the blue frame becomes the black cell.
Let's think of two cream colored groups in the upper left. Either of the orange frames will be a black cell, so at the moment there are an odd number of black cells in the cream group. In order to add two black mas to each group, the number of black cells must be even. Then one cell must be paired with a cell other than these groups The only other cells that can be paired with other group cells is red framed cell, so red framed cell is black cell.
There are many other methods.You can solve it faster if you remember what you think and find.
ex11



2020.3.2 Modified
2020.1.25 First edition
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