from lib import * input = read_input(2016, 21) import re def scramble(inp): (*out,) = inp for line in input.splitlines(): if match := re.match(r"^swap position (\d+) with position (\d+)$", line): x, y = map(int, match.groups()) out[x], out[y] = out[y], out[x] if match := re.match(r"^swap letter ([a-zA-Z\d]+) with letter ([a-zA-Z\d]+)$", line): x, y = match.groups() out = [[[c, x][c == y], y][c == x] for c in out] if match := re.match(r"^rotate (left|right) (\d+) steps?$", line): d, n = match.groups() n = int(n) if d == "right": n *= -1 n %= len(out) out = out[n:] + out[:n] if match := re.match(r"^rotate based on position of letter ([a-zA-Z\d]+)$", line): (x,) = match.groups() idx = out.index(x) n = -(1 + idx + (idx >= 4)) % len(out) out = out[n:] + out[:n] if match := re.match(r"^reverse positions (\d+) through (\d+)$", line): x, y = sorted(map(int, match.groups())) out = out[:x] + out[x : y + 1][::-1] + out[y + 1 :] if match := re.match(r"^move position (\d+) to position (\d+)$", line): x, y = map(int, match.groups()) out.insert(y, out.pop(x)) return "".join(out) print(scramble("abcdefgh")) for it in itertools.permutations("abcdefgh"): if scramble(inp := "".join(it)) == "fbgdceah": print(inp) break