diff --git a/2024/ruby/day_10.rb b/2024/ruby/day_10.rb
index daca967..a096c76 100644
--- a/2024/ruby/day_10.rb
+++ b/2024/ruby/day_10.rb
@@ -5,75 +5,31 @@ map = DATA.readlines(chomp: true).flat_map.with_index {|row, y|
}.to_h
trailheads = map.filter_map { _2 == 0 && _1}
-# trailends = map.select { _2 == 9 }
DELTAS = [[-1, 0], [1, 0], [0, -1], [0, 1]]
-def trailends(map, head)
- queue = [head]
- visited = Set.new
- until queue.empty?
- current = queue.shift
- visited << current
+def trails(map, head)
+ active = [[head]]
+ finished = []
+ until active.empty?
+ current = active.shift
- queue.concat(
- DELTAS
- .map {|d| current.zip(d).map { _1 + _2 } }
- .select { map.fetch(_1, nil) == map.fetch(current) + 1 }
- .reject { visited.include?(_1) }
- )
+ steps = DELTAS
+ .map {|d| current.last.zip(d).map { _1 + _2 } }
+ .select { map.fetch(_1, nil) == map.fetch(current.last) + 1 }
+
+ if steps.empty?
+ finished << current
+ else
+ active.concat(steps.map { current + [_1] })
+ end
end
- visited.select { map.fetch(_1) == 9 }
+
+ finished
+ .select { _1.length > 2 && map.fetch(_1.last) == 9 }
+ .uniq
end
-pp trailheads.sum { trailends(map, _1).length }
+pp trailheads.sum { trails(map, _1).length }
__END__
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