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Poor man's trie

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Bert Peters
2024-12-19 22:35:55 +01:00
parent 891a5ea50c
commit dd07090056
1 changed files with 13 additions and 8 deletions
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21
2024/src/aoc/days/day19.py
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@@ -1,12 +1,13 @@
import collections
import functools import functools
from . import CombinedRunner from . import CombinedRunner
def parse_input(data: str) -> tuple[tuple[str, ...], list[str]]: def parse_input(data: str) -> tuple[list[str], list[str]]:
patterns, designs = data.strip().split("\n\n") patterns, designs = data.strip().split("\n\n")
return tuple(patterns.split(", ")), designs.split("\n") return patterns.split(", "), designs.split("\n")
class DayRunner(CombinedRunner): class DayRunner(CombinedRunner):
@@ -14,6 +15,10 @@ class DayRunner(CombinedRunner):
def run_both(cls, input: str) -> int: def run_both(cls, input: str) -> int:
patterns, designs = parse_input(input) patterns, designs = parse_input(input)
by_prefix = collections.defaultdict(list)
for prefix in patterns:
by_prefix[prefix[0]].append(prefix)
possible = 0 possible = 0
ways = 0 ways = 0
@@ -21,12 +26,12 @@ class DayRunner(CombinedRunner):
def is_possible(design: str) -> bool: def is_possible(design: str) -> bool:
if not design: if not design:
return 1 return 1
else:
return sum( return sum(
is_possible(design[len(pat) :]) is_possible(design[len(prefix) :])
for pat in patterns for prefix in by_prefix[design[0]]
if design.startswith(pat) if design.startswith(prefix)
) )
for design in designs: for design in designs:
if (solve := is_possible(design)) > 0: if (solve := is_possible(design)) > 0: