Riddles, brain puzzles and mathematical problems

[Froge]

I lied. It's not an algorithm, more like a mapping.

Spoiler below!

Move W1, W2, B2 to everything below 4, move B1 to 5, move both whites back to stuff before 4, place B2 at 6, move all the whites out to stuff below 4, move B2 beside B1, place whites wherever at 1 or 6 to finish.

Next question:

This crudely drawn circuit has 3 switches on top and 2 at bottom. The probability that any switch is open is 1/3.

Find the probability that a current can travel across this circuit.