this post was submitted on 24 Dec 2024
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Advent Of Code
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Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.
AoC 2024
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console.log('Hello World')
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Yeah - dumped out the input into GraphViz, and then inspected it 'by eye' to get the swaps. Nearly finished in the top 100 in the world, too. Feels like a really bad way to get the solution, though.
If you add eg. 1111 and 1111 and expect 11110, then you'll get an output like 11010 if there's a mistake in "bit 2". Can try all the swaps between x2 / y2 / z2 until you get the "right answer", and then continue. There's only about five different ops for each "bit" of the input, so trying all of them won't take too long.
Im halfway through doing that, definitely feels wrong though. I'm curious to see if there is a good programatic way of doing it.
Dont you need a pair of broken bits? For mine, bit 6 is broken, because its just x6^y6. So I need to find where the carry bit got swapped to. Or are you suggesting that I swap my bit 6 operation with every other operation until it resolves?
In my input (and I suppose in everyone else's too) the swaps only occurred within the adder subcircuit for a single bit. In general, however, the way the problem is phrased, any two outputs can be swapped, which can lead to two broken bits per swap (but this just doesn't happen).
Mine definitely had outputs swapped between adders,
z06was justx06 XOR y06. The circuit was completely broken there.