Solving part2 first club++.
I guess the functional language forces us to think recursively, although I found it quite hard to reason about Part 1, it turned out I just needed to add a uniq call to the part 2 solution.
def part1({grid, zeros}) do
zeros
|> Enum.map(fn point -> point |> find_trails(grid, 0) |> Enum.uniq() |> Enum.count() end)
|> Enum.sum()
end
def find_trails(point, _grid, 9), do: [point]
def find_trails({x, y}, grid, height) do
find_neighbours(x, y, height + 1, grid)
|> Enum.flat_map(fn {point, _} -> find_trails(point, grid, height + 1) end)
end
def find_neighbours(x, y, height, grid) do
grid
|> Map.take([{x - 1, y}, {x + 1, y}, {x, y - 1}, {x, y + 1}])
|> Enum.filter(&match?({_, ^height}, &1))
end
https://git.adamu.jp/adam/AdventOfCode/src/branch/main/2024/day10.exs
