aoc-2016/12.py

#!/usr/bin/python3

with open('12.txt', 'r') as file:
    instr = list(map(str.split, map(str.strip, file.readlines())))

def value(x):
    try:
        return int(x)
    except ValueError:
        return registers[x]

def cpy(args): registers[args[1]] = value(args[0])
def inc(args): registers[args[0]] += 1
def dec(args): registers[args[0]] -= 1
def jnz(args): global pc; pc += (0 if value(args[0]) == 0 else value(args[1]) - 1)

def run():
    global pc
    while pc < len(instr):
        globals()[instr[pc][0]](instr[pc][1:])
        pc += 1

registers = {'a': 0, 'b': 0, 'c': 0, 'd': 0}
pc = 0
run()

print("Stage 1: %s" % registers['a'])

registers = {'a': 0, 'b': 0, 'c': 1, 'd': 0}
pc = 0
run()

print("Stage 2: %s" % registers['a'])