Minimum step recovery:

The most difficult game, in this game or competition, you can't turn the Rubik's cube, you can only observe the state of the Rubik's cube with your eyes, and then think about the least steps to solve the Rubik's cube. Although no one can prove what is the biggest upset state of the Rubik's cube (that is, the state that needs to be restored with the most steps), it is generally believed that the third-order Rubik's cube can reach the maximum state by randomly disrupting it for 50 steps, and it takes 23 steps to restore it to its original state. The current world record is 28 steps to reduce the burden.

Friedrich method:

Fridrich method is actually a variant of hierarchical method, but because it summarizes various possible situations, it will increase the memory many times (more than 100 formulas), and its steps are divided into the following points:

6? 1 Turn the bottom layer out of a cross that conforms to the color block distribution.

6? 1 There are 4 1 formulas to reset the bottom corner block and the corresponding side block at the same time (F2L, fisrt 2 layer).

6? At the top of 1, 57 formulas are used to make the cOLor uniform (ol, the last layer of O rite).

6? 1 There are 2 1 formulas to unify the color of the top surface (PLL).

At present, most Rubik's cube masters use Fridrich method, because the memory of more than 100 formulas is not much compared with the speed they can achieve.