99 lines
2.9 KiB
Python
99 lines
2.9 KiB
Python
from heapq import heappush, heappop
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from tools.aoc import AOCDay
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from tools.coordinate import Coordinate
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from tools.grid import Grid
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from typing import Any
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def get_dijkstra_path(height_map: Grid, start: Coordinate, end: Coordinate) -> list | None:
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f_costs = []
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openNodes = {}
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closedNodes = {}
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openNodes[start] = (0, start.getDistanceTo(end), None)
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heappush(f_costs, (0, start))
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while f_costs:
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_, currentCoord = heappop(f_costs)
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if currentCoord not in openNodes:
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continue
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currentNode = openNodes[currentCoord]
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closedNodes[currentCoord] = currentNode
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del openNodes[currentCoord]
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if currentCoord == end:
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break
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for neighbour in height_map.getNeighboursOf(currentCoord, includeDiagonal=False):
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if neighbour in closedNodes or height_map.get(neighbour) - 1 > height_map.get(currentCoord):
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continue
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neighbourDist = 1
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targetDist = neighbour.getDistanceTo(end)
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f_cost = targetDist + neighbourDist + currentNode[1]
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if neighbour not in openNodes or f_cost < openNodes[neighbour][0]:
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openNodes[neighbour] = (f_cost, currentNode[1] + neighbourDist, currentCoord)
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heappush(f_costs, (f_cost, neighbour))
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if end not in closedNodes:
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return None
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else:
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currentNode = closedNodes[end]
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pathCoords = [end]
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while currentNode[2]:
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pathCoords.append(currentNode[2])
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currentNode = closedNodes[currentNode[2]]
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return pathCoords
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class Day(AOCDay):
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inputs = [
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[
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(31, "input12_test"),
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(423, "input12"),
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],
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[
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(29, "input12_test"),
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(416, "input12"),
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]
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]
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def get_map(self) -> (Grid, Coordinate, Coordinate):
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grid = Grid(30)
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start = None
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end = None
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for y, line in enumerate(self.getInput()):
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for x, char in enumerate(line):
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if char == 'S':
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start = Coordinate(x, y)
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grid.set(start, 0)
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elif char == 'E':
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end = Coordinate(x, y)
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grid.set(end, 25)
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else:
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grid.set(Coordinate(x, y), ord(char) - ord('a'))
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return grid, start, end
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def part1(self) -> Any:
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return len(get_dijkstra_path(*self.get_map())) - 1
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def part2(self) -> Any:
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min_steps = float("inf")
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height_map, start, end = self.get_map()
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for c in height_map.getActiveCells():
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if height_map.get(c) == 0:
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steps_from_here = get_dijkstra_path(height_map, c, end)
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if steps_from_here is not None and len(steps_from_here) < min_steps:
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min_steps = len(steps_from_here)
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return min_steps - 1
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if __name__ == '__main__':
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day = Day(2022, 12)
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day.run(verbose=True)
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