Rules and how to solve Shikaku.
Rules
  1. Divide some cells into rectangular groups surrounded by thick lines to meet the following conditions.
  2. The white numbers in black circle are the problem cells, and the numbers indicate the number of cells in the rectangular group that includes this cell.
  3. A rectangular group surrounded by a bold line always contains one problem cell. Do not enter the problem cell or do not enter two.
  4. A cell belongs to only one group and does not belong to more than one group.


jump to Shikaku problem.
Tips for solving
まず問題で与えられた数となる長方形の種類を考えてみます。③であれば1×3と3×1の長方形しかありませんが、 ⑫であれば1×12、12×1、2×6、6×2、3×4、4×3と6通りあります。
始めは大きな数字や、組み合わせ数の少ない3,5,7などの数字に注目します。
これらの数字で一通りしか四角形を決めようがない所からまず四角形を決めましょう。
それでは例題で説明します。
First consider the type of rectangle given in the problem number. In case of ③, there are only 1 × 3 and 3 × 1 rectangles, For ⑫, there are six types, 1 × 12, 12 × 1, 2 × 6, 6 × 2, 3 × 4, 4 × 3.
At first focus on large numbers or numbers with few combinations such as 3,5,7.
First of all, let's decide the rectangle from the place where it is impossible to decide the rectangle except one combination by these numbers.
Let me explain with an example.
The following figure is the problem. Cells with numbers are the problem.
Here, please pay attention to ⑤ on the bottom line.There are only 1 × 5 and 5 × 1 rectangles that have 5 cells. We will make a group of 5 vertically or a group of 5 horizontally including this problem square, Because there is a ⑥ in the top row, you cannot make a group of 5 vertically.
ex0
As shown in the following figure, the bottom row is a group of one horizontal row with five cells.
Next, let's look at ⑥ in the top line. There are four types of rectangles with the number of cell of 6: 1 × 6, 6 × 1, 2 × 3, 3 × 2. In this problem, it is not possible to create a group of 6 cells. It becomes a 2x3, 3x2 rectangle. Right now, you can make both 2x3 and 3x2 rectangles that include the top ⑥, but the red framed cell on the left does not belong to these rectangles.
Then, the rectangle containing this red frame can only be combined with the cell ② below to create a 1x2 rectangle.
ex1
Let's think again at the top ⑥.
The group containing this ⑥ can be 2 × 3 or 3 × 2. A 2x3 group can be composed of a red frame as shown below but if you create such a group, you will not be able to create a group of six cells specified by the green problem cell ⑥ in the second row from the bottom. Therefore, the group specified by the problem cell ⑥ at the top is a 3 × 2 group.
In this problem, there was only one way to create a 3x2 group, but there are usually multiple ways to create a group, so be careful not to overlook it.
ex2
Now consider the blue framed cell in the upper left corner. A group that includes this cell can only create a group of four cells specified by the problem cell ④ 2 below this cell. ex3
All you have to do is divide it into two rectangles designated by the green frame ② and ⑥. ex4
This is the correct solution. ex5



2020.3.3 Modified
2010.6.13 First edition
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