I am wondering if manual inspection is the way to go for pt2? Seems almost achievable with some formatting. Anyone been down this road?

  • CameronDev@programming.devOPM
    2·
    3 days ago

    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?

    • hades@lemm.ee
      4·
      3 days ago

      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).

      • CameronDev@programming.devOPM
        2·
        3 days ago

        Mine definitely had outputs swapped between adders, z06 was just x06 XOR y06. The circuit was completely broken there.

    • addie@feddit.uk
      3·
      3 days ago

      Every “pair” of bits has the same pattern of AND and XOR, and the previous “carry bit” is passed into the same OR / (XOR + AND) combo to produce an output bit and the next “carry bit”. The “whole chain” is nearly right - otherwise your 44 bit inputs wouldn’t give a 45 bit output - it’s just a few are swapped over. (In my case, anyway - haven’t seen any others.) All my swaps were either in the “same column” of GraphViz output, or the next column.

      So, yeah. Either “random swaps” with “nearby” outputs, because it’s nearly right and you don’t need to check further away; or use the fact that this is the well-known pattern for adding two numbers in a CPU’s ALU to generate the “correct” sequence, identify which ones are wrong, and output them in alphabetical order… The answer you need doesn’t even require you to pair them up.