You decide to head directly to the CPU and fix the printer from there. As you get close, you find an experimental coprocessor doing so much work that the local programs are afraid it will halt and catch fire. This would cause serious issues for the rest of the computer, so you head in and see what you can do.

The code it's running seems to be a variant of the kind you saw recently on that tablet. The general functionality seems very similar, but some of the instructions are different:

Read the full puzzle.

using System;
using System.Collections.Generic;

namespace AdventOfCode.Y2017.Day23;

[ProblemName("Coprocessor Conflagration")]
class Solution : Solver {

    public object PartOne(string input) {
        var regs = new Dictionary<string, int>();
        int ip = 0;
        int getReg(string reg) {
            return int.TryParse(reg, out var n) ? n
                : regs.ContainsKey(reg) ? regs[reg]
                : 0;
        }
        void setReg(string reg, int value) {
            regs[reg] = value;
        }

        var prog = input.Split('\n');
        var mulCount = 0;
        while (ip >= 0 && ip < prog.Length) {
            var line = prog[ip];
            var parts = line.Split(' ');
            switch (parts[0]) {
                case "set":
                    setReg(parts[1], getReg(parts[2]));
                    ip++;
                    break;
                case "sub":
                    setReg(parts[1], getReg(parts[1]) - getReg(parts[2]));
                    ip++;
                    break;
                case "mul":
                    mulCount++;
                    setReg(parts[1], getReg(parts[1]) * getReg(parts[2]));
                    ip++;
                    break;
                case "jnz":
                    ip += getReg(parts[1]) != 0 ? getReg(parts[2]) : 1;
                    break;
                default: throw new Exception("Cannot parse " + line);
            }
        }
        return mulCount;
    }

    public object PartTwo(string input) {
        var c = 0;
        for (int b = 107900; b <= 124900; b += 17) {
            if (!IsPrime(b)) {
                c++;
            }
        }
        return c;
    }

    bool IsPrime(int n) {
        for (int j = 2; j * j <= n; j++) {
            if (n % j == 0) return false;
        }
        return true;
    }

}

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