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Solve day12 part 2

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Gabriel Augendre 2022-12-12 18:27:52 +01:00
parent 08863aeb5a
commit 746b5ad9a8
1 changed files with 18 additions and 4 deletions
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22
2022/day12_hill.py
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@ -1,6 +1,7 @@
from __future__ import annotations from __future__ import annotations
import dataclasses import dataclasses
import math
import networkx as nx import networkx as nx
from networkx.algorithms.shortest_paths.generic import shortest_path from networkx.algorithms.shortest_paths.generic import shortest_path
@ -43,6 +44,7 @@ class Hill:
end: Cell end: Cell
width: int width: int
height: int height: int
potential_starters: list[Cell]
graph: nx.DiGraph = None graph: nx.DiGraph = None
def top(self, cell: Cell) -> Cell | None: def top(self, cell: Cell) -> Cell | None:
@ -97,6 +99,7 @@ def parse_data(data: list[str]) -> DataType:
end_cell = None end_cell = None
height = len(data) height = len(data)
width = len(data[0]) width = len(data[0])
potential_starters = []
for y, row in enumerate(data): for y, row in enumerate(data):
for x, char in enumerate(row): for x, char in enumerate(row):
start, end = False, False start, end = False, False
@ -113,7 +116,9 @@ def parse_data(data: list[str]) -> DataType:
elif end: elif end:
end_cell = cell end_cell = cell
cells.append(cell) cells.append(cell)
hill = Hill(cells, start_cell, end_cell, width, height) if char == "a":
potential_starters.append(cell)
hill = Hill(cells, start_cell, end_cell, width, height, potential_starters)
hill.build_graph() hill.build_graph()
return hill return hill
@ -124,9 +129,18 @@ def solve_part_1(data: DataType) -> int:
def solve_part_2(data: DataType) -> int: def solve_part_2(data: DataType) -> int:
return 0 min_length = math.inf
for candidate in data.potential_starters:
try:
path = shortest_path(data.graph, candidate, data.end)
path_length = len(path)
except nx.NetworkXNoPath:
path_length = math.inf
if path_length < min_length:
min_length = path_length
return min_length - 1
if __name__ == "__main__": if __name__ == "__main__":
main("inputs/day12-test1", expected_part_1=31) main("inputs/day12-test1", expected_part_1=31, expected_part_2=29)
main("inputs/day12", expected_part_1=456) main("inputs/day12", expected_part_1=456, expected_part_2=454)