Material preparation: Huarong Road.

The operation steps are as follows:

The rule of 1. indicates that the final layout of squares should be arranged in order from 1. Moving back and forth, 1 to 3 is easier to arrange, so you need to move 4 to the upper right corner. Three, four can't retreat without moving.

2. Move 1 first, and then keep 1 to 3 continuously, so that you can put 4 in the upper right corner and complete the first line.

3. The second line uses the same method, that is, keep the first three consecutive digits, and then move the fourth digit back, so that it can be arranged.

All right.

4. After the third row is finished, if it is not cleared, it will still be the fourth row.

5. On the whole, in order to complete the four lines, it is necessary to process them into 9, 10 left column and1,12 right column, and then arrange 13 to 15 in an L shape.

6. Finally, drag the slider in the direction of the arrow to reset it all, and it is customs clearance.