diff --git a/2016-python2/output/day_14.py b/2016-python2/output/day_14.py new file mode 100644 index 0000000..01e96ae --- /dev/null +++ b/2016-python2/output/day_14.py @@ -0,0 +1,75 @@ +import functools +import re +from hashlib import md5 + +from output import answer # , matrix, D, DD, ADJ, ints, mhd, mdbg, vdbg + +n = 14 +title = "One-Time Pad" + + +@answer(1, "64th key is at index {}") +def part_1(presolved): + return presolved[0] + + +@answer(2, "64th key is at index {} using key stretching") +def part_2(presolved): + return presolved[1] + + +def solve(s): + p1 = run(s) + p2 = run(s, p2=True) + return p1, p2 + + +def run(s, p2=False): + r3 = re.compile(r"(\w)\1{2}") + c = 0 + i = 0 + H = md5(s.encode()) + while True: + i += 1 + if p2: + a = stretch(f"{s}{i}") + else: + Ha = H.copy() + Ha.update(str(i).encode()) + a = Ha.hexdigest() + if m := re.search(r3, a): + x = m.group(1) + r5 = re.compile(r"(" + x + r")\1{4}") + for j in range(1000): + if p2: + b = stretch(f"{s}{str(i + 1 + j)}") + else: + Hb = H.copy() + Hb.update(str(i + 1 + j).encode()) + b = Hb.hexdigest() + if re.search(r5, b): + c += 1 + break + if c == 64: + break + return i + + +@functools.lru_cache(maxsize=None) +def stretch(s): + for _ in range(2017): + s = md5(s.encode()).hexdigest() + return s + + +if __name__ == "__main__": + with open("./input/14.txt", "r") as f: + inp = f.read().strip() + + inp = solve(inp) + + a = part_1(inp) + b = part_2(inp) + + assert a == 18626 + assert b == 20092