CFOP Quick-witted Princess Leia (F2L+OLL completion)

[Tito_H]

Episode XX+8

Princess Leia
and R2D2 are on
their way home after
successfully freeing themselves
from the indigenous tribes on the moon
Endor, but a Predestination Paradox occurs
in a nearby space-time space, sending them back
in time and once again finding themselves under attack by Imperial soldiers at the fortress' back entrance...

Princess Leia instructed R2D2, "The way to open this iron door must be to solve a Rubik's Cube. Please find it quickly." R2D2 accessed the fortress's host computer, found the problem to be solved, and projected the Rubik's Cube and instructions into the air.

The Rubik's Cube was scrambled as shown below, and the instructions read, "Complete F2L+OLL in 8 moves or less."

(Cube position: Yellow top & Blue front)


Princess Leia quickly came up with an algorithm that could be completed in 8 moves, and turned the projection cube.

(Princess Leia's solve)


However, the iron door didn't budge.

Princess Leia said, "No, it won't work. Like last time, I need to complete it in 8 moves or less using a QTM-based approach instead of an STM-based approach."

She instructed R2D2, "Just like last time, hack into the host computer, swap the letters 'QTM' and 'STM' in the source code, and reboot it."

After a while, R2D2 replied, "Princess Leia, the source code is now written in read-only mode and cannot be rewritten. There is evidence that an Imperial programmer did this shortly before us."

Princess Leia regretted, "Damn. They beat us to it." Just then, a bullet fired by an Imperial soldier hit R2D2, causing him to burst into flames. He then said in agony, "Part of my memory has malfunctioned, causing my calculation speed to drop by a hundredth. It may take several minutes to find a solve to meet the instructions."

Princess Leia muttered, "That's not enough time to escape enemy fire. What should I do...?"

Can someone help her?

 

[Tito_H]

Let's see how Princess Leia and R2D2 overcame this difficult situation.

While Princess Leia was at her wit's end, R2D2, who was connected to the Imperial fortress's host computer, said, "Princess Leia, I have discovered that this fortress is equipped with the Setun-70, a ternary computer created by the former Soviet Union.

In binary, the number 8 is 1000, and 10 is 1010. Therefore, the computer determines that 1000 < 1010, so 8 moves < 10 moves. However, in ternary, the number 10 is 101. If it were to compare the binary number 8 with the ternary number 10, it would incorrectly determine that 1000 > 101, so 8 moves > 10 moves.

Fortunately, I was able to switch to debug mode, so I was able to capture the moment your 10-move solve completed and entered the decision routine. At that moment, I will interfere with the arithmetic register, forcing their system to use Setun-70 for the calculations.” And he began his work.

Princess Leia, not really understanding what was going on, ran the same 10-move solve with the cube projected in the air.

For a while, nothing happened...

Just as Princess Leia was barely able to fend off the enemy's attacks, the iron doors of the fortress roared open!

It seemed R2D2's plan had worked.
R2D2, you are the savior!

 

[Tito_H]

By the way, the alg I set to complete F2L+OLL in this scrambled cube in 8 moves based on QTM is R U R' F D R' D' F'.

First, we put the EP of the BR slot in the FR slot (the pair in the FR slot goes to the U face), and then use the F2L alg to the back slot, which is something that intermediate level cubers might know (the FR pair on the U face is also slotted in).