from utils import open_day from functools import cache from dataclasses import dataclass from itertools import count, chain import re @dataclass class Node: flow: int neighbours: list[tuple[str, int]] ids = {'AA': 0} rids = {0: 'AA'} nextid = 1 def intern(n): global nextid if n in ids: return ids[n] ids[n] = nextid rids[nextid] = n nextid += 1 return nextid - 1 def extern(i): return rids[i] regex = re.compile(r'^Valve (..) has flow rate=([0-9]+); tunnels? leads? to valves? (.*)$') inp = {} with open_day(16) as f: for line in f: m = regex.match(line) assert(m) valve, flow, neighbours = m.group(1, 2, 3) inp[valve] = (int(flow), neighbours.split(', ')) nodes = {} for valve, (flow, neighbours) in inp.items(): if valve != 'AA' and flow == 0: continue actual_neighbours = [] for n in neighbours: prev = valve for cost in count(1): if n == 'AA' or inp[n][0] != 0: break l, r = inp[n][1] nnext = r if l == prev else l prev = n n = nnext actual_neighbours.append((intern(n), cost)) nodes[intern(valve)] = Node(flow, actual_neighbours) @cache def sum_flow(open_valves): total = 0 for i in count(): if not open_valves: break if open_valves & 1: total += nodes[i].flow open_valves >>= 1 return total recurse_cache = dict() def recurse(open_valves=1, current=0, flow=0, time_left=30, path=[]): key = (current, flow, time_left) if key in recurse_cache: return recurse_cache[key] cnode = nodes[current] best = flow, path def check(open_valves, current, flow, time_left): nonlocal best new = recurse(open_valves, current, flow, time_left, path + [current]) if new[0] > best[0]: best = new for neighbour, cost in cnode.neighbours: if cost >= time_left: continue check(open_valves, neighbour, flow, time_left - cost) if not (open_valves & (1 << current)) and time_left > 0: check(open_valves | 1 << current, current, flow + cnode.flow * (time_left - 1), time_left - 1) recurse_cache[key] = best return best v, p = recurse() print(v, [extern(s) for s in p])