[2022][day 16] add part 1 solution

2022/AOC16.py

@@ -1,8 +1,5 @@
-import functools
 import heapq
 import itertools
-from collections import defaultdict
-
 import parse
 from typing import List, Tuple, Set
 
@@ -65,38 +62,46 @@ def build_network(valves, network):
  (end, 1 + dist, pressure)
  ) # +1 for opening valve
 
- return enhanced_network
+ return enhanced_network, valves
 
 
 def part1(valves, network):
- network = build_network(valves, network)
+ network, valves = build_network(valves, network)
 
- def find_path(t: int, valve: str, state) -> int:
- # TODO USE CACHE
+ def find_path(t: int, valve: str, state: Tuple[str, int], seen) -> int:
  current_pressure = sum(
- (opened_time - t) * pressure for pressure, opened_time in state.values()
+ (opened_time - t) * valves[v] for v, opened_time in state
  )
- if t <= 0:
+ if seen.get((t, valve), -1) >= current_pressure:
+ return 0
+ seen[t, valve] = current_pressure
+
+ if t <= 0 or len(state) == len(valves):
  return current_pressure
 
  # choice 1: wait
- wait = find_path(t - 1, valve, state)
+ wait = find_path(t - 1, valve, state, seen)
 
  # 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)
+ opened_valves = [v for v, _ in state]
+ if new_valve not in opened_valves and t - dist > 0:
+ new_state = [
+ (v, tt) for v, tt in state
+ ] # convert tuple to list to add new element
+ new_state.append((new_valve, t - dist))
+ new_pressure = find_path(
+ t - dist, new_valve, tuple(new_state), seen
+ ) # convert back
  max_new_valve = max(max_new_valve, new_pressure)
 
  return max(wait, max_new_valve)
 
- return find_path(30, "AA", {})
+ return find_path(27, "AA", (), {})
 
 
 @timer
@@ -108,6 +113,6 @@ def main(filename: str) -> Solution:
 
 
 if __name__ == "__main__":
- part_1_solution, part_2_solution = main("aoc16.txt") # 6:54
- print(f"PART 1: {part_1_solution}") #
+ part_1_solution, part_2_solution = main("aoc16.txt")
+ print(f"PART 1: {part_1_solution}") # 1789
  print(f"PART 2: {part_2_solution}") #