Advent of Code 2020, now in the most terse and awful python possible
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#!/usr/bin/env python3
from sys import argv
p = []
for x in open(argv[1]):
x = x.strip().split()
p.append((x[0], int(x[1])))
class Cpu:
def __init__(self, prog):
self.prog = prog
self.pc = 0
self.a = 0
return
def i_nop(self, arg):
return
def i_acc(self, arg):
self.a += arg
return
def i_jmp(self, arg):
self.pc += arg - 1
return
def step(self):
if self.pc >= len(self.prog):
return False
i = self.prog[self.pc]
self.pc += 1
instr = {
"nop": self.i_nop,
"acc": self.i_acc,
"jmp": self.i_jmp
}
instr[i[0]](*i[1:])
return True
def halts(p):
c = Cpu(p)
seen = set()
while True:
if c.pc in seen:
return (False, c.a)
seen.add(c.pc)
if not c.step():
return (True, c.a)
print(halts(p)[1])
for i, ins in enumerate(p):
n = None
if ins[0] == "jmp":
n = p[i]
p[i] = ("nop", ins[1])
elif ins[0] == "nop":
n = p[i]
p[i] = ("jmp", ins[1])
else:
continue
a = halts(p)
if a[0]:
print(a[1])
break
p[i] = n