27 ms·
Start from the last step: AB BA From here, flipping two opposit corners will result in all 4 being the same way. One step before: AA BB Flip
by NoodleIncident 12y ago
Start from the last step:
AB
BA
From here, flipping two opposit corners will result in all 4 being the same way. One step before:
AA
BB
Flipping any two adjacent ones will either solve it or get you to the previous step.
So from here, we can see that any state with two up and two down is solvable. The state with all four one way or the other is already solved. The only thing left is the state with just one out of line.
AB
BB
No matter which individual one is flipped, you are in a solvable state.