[2022][day 16] current state of solution

2022/AOC16.py

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+import functools
+import heapq
+import itertools
+from collections import defaultdict
+
+import parse
+from typing import List, Tuple, Set
+
+from _utils import read_input, timer, Solution
+
+
+def process_input(filename: str):
+ _input = read_input(filename)
+
+ valves = {}
+ network = {}
+ for line in _input:
+ line = line.replace("valves", "valve").replace("tunnel leads", "tunnels lead")
+ parsed_line = parse.parse(
+ "Valve {start} has flow rate={flow_rate}; tunnels lead to valve {end}", line
+ )
+ start, flow_rate, end = (
+ parsed_line["start"],
+ int(parsed_line["flow_rate"]),
+ parsed_line["end"].replace(" ", ""),
+ )
+ valves[start] = flow_rate
+ network[start] = end.split(",")
+ return valves, network
+
+
+def find_shortest_path(network, start: str, end: str) -> int:
+ queue = []
+ heapq.heappush(queue, (0, start))
+ visited = set()
+
+ while queue:
+ steps, current_node = heapq.heappop(queue)
+
+ if current_node == end:
+ return steps
+ elif current_node not in visited:
+ visited.add(current_node)
+
+ neighbors = network[current_node]
+ for next_node in neighbors:
+ if next_node not in visited:
+ heapq.heappush(queue, (steps + 1, next_node))
+
+ return -1
+
+
+def build_network(valves, network):
+ nodes = {n for n in network}
+ enhanced_network = {}
+
+ for (start, end) in itertools.product(nodes, nodes):
+ dist = find_shortest_path(network, start, end)
+ pressure = valves[end]
+ if dist > 0 and pressure > 0:
+ if start not in enhanced_network:
+ enhanced_network[start] = [(end, 1 + dist, pressure)]
+ else:
+ enhanced_network[start].append(
+ (end, 1 + dist, pressure)
+ ) # +1 for opening valve
+
+ return enhanced_network
+
+
+def part1(valves, network):
+ network = build_network(valves, network)
+
+ def find_path(t: int, valve: str, state) -> int:
+ # TODO USE CACHE
+ current_pressure = sum(
+ (opened_time - t) * pressure for pressure, opened_time in state.values()
+ )
+ if t <= 0:
+ return current_pressure
+
+ # choice 1: wait
+ wait = find_path(t - 1, valve, state)
+
+ # choice 2: move to unopened valve and open it
+ # (!important: only USEFUL valves + eliminate state where move solely!)
+ # (requires precomputing distances from current valve to neighbors w/ >0 pressure flow)
+ max_new_valve = 0
+ neighbors = network[valve]
+ for new_valve, dist, p in neighbors:
+ if new_valve not in state and t - dist > 0:
+ new_state = state.copy()
+ new_state[new_valve] = p, t - dist # valve pressure, time opened
+ new_pressure = find_path(t - dist, new_valve, new_state)
+ max_new_valve = max(max_new_valve, new_pressure)
+
+ return max(wait, max_new_valve)
+
+ return find_path(30, "AA", {})
+
+
+@timer
+def main(filename: str) -> Solution:
+ valves, network = process_input(filename)
+ part_1_solution = part1(valves, network)
+ part_2_solution = 0
+ return part_1_solution, part_2_solution
+
+
+if __name__ == "__main__":
+ part_1_solution, part_2_solution = main("aoc16.txt") # 6:54
+ print(f"PART 1: {part_1_solution}") #
+ print(f"PART 2: {part_2_solution}") #