Life is A Test 2: Test Harder (Quite A Bit Harder)

by Brony_of_Brody

All Is (Mostly) Resolved

Having finally secured the crab, you and Applejack eventually manage to find a way to subdue it: Apple-Crabs can apparently be rendered catatonic when exposed to oranges, and although it does nothing to not fuel Applejack's belief that apples are the only answer, it does at least solve your current crisis.

Applejack has half a mind to march up to Flim and Flam and get your money back, but as it's been seven hours since you purchased the mecha-trap, you reason they must have skipped town and taken all the cash with you. Your poor bits. You will never see them again...

...or will you? As it happens, as the brothers were trying to skip town, they were intercepted by Princess Twilight Sparkle, along with a mob of angry ponies whose livelihoods were almost destroyed by these transforming robots, and made to pay restitution for all their meddling. A mecha battle in the middle of Sweet Apple Acres was hardly going to go unnoticed, after all, especially not by the Princess of Friendship. (It does make you ask why nopony tried to help, but you know pony herd mentality.)

After you shake down the pair for all the almost pennies you paid for the device, the brothers try to hastily leave...only to discover that the locomotive they arrived in Ponyville with won't start. Much to their embarrassment, it would seem that the angry mob has vandalised their precious vehicle, and will no longer start. They implore you to help, as they are currently a little too preoccupied being splattered with various fruits and vegetables and being jeered at by the townsponies to fix the machine themselves. Sadly, your oath is to help everypony, so keeping a mental note to fleece the brothers for every single last bit on them as your fee, you open it up.

You are greeted by what appear to be a jumbled up mess of four identical looking wires. when you crack open the right side of the locomotive, you see the other ends of the wires, but you have absolutely no way of telling which end of the wires are which from just a cursory glance. Flam just about manages to splutter out that you can get the vehicle to start again as long as two of the cables are joined at one end together, and then linked to form a loop. Form two complete circuits, and it should work again, allowing Flim and Flam to flee from their overstayed welcome.

As much as you would love to dawdle and allow the brothers more time to have so much abuse heaped on them, time is precious to you, and so you want to waste as few trips as possible walking from one side of Flim and Flam's locomotive to the other. Your first test is to tell you that two cables are either A and B, or B and A. So what's the quickest way to get the thing fixed so everypony can be on their way?

Author's Note:

And that's that. Probably. Oh who am I kidding, of course it isn't.

1. Four electric cables in Flim and Flam's machine.
2. All four look identical, and are randomly jumbled, making it impossible to tell them apart.
3. You want to join two of the cables together at one end, and on the other end see which two cables form a complete circuit.

PUZZLE: How many trips will you need to one end and back again to label all four cables correctly?

Comments

[farsan]

Only two round trips.

Let's name the cables from one end 1-4

First check: Connect 1 and 2. It will connect two letters on the other end, let's name them X and Y.
Second check: Connect 1 and 3: Two letters will result, one in common with the first check. Let's name them X and Z. Then, 1 = X, 2 = Y, 3 = Z and 4 is the remaining one.