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| use crate::common::Solution; | |
| use crate::grid::{Grid,GridElement,Position}; | |
| #[derive(Eq,PartialEq,Clone,Debug)] | |
| enum ForestTile { | |
| Open, | |
| Tree, | |
| } | |
| impl GridElement for ForestTile { | |
| fn from_char(c: &char) -> Option<ForestTile> { | |
| match c { | |
| '.' => Some(ForestTile::Open), | |
| '#' => Some(ForestTile::Tree), | |
| _ => None, | |
| } | |
| } | |
| } | |
| pub fn solve(lines: &[String]) -> Solution { | |
| let grid: Grid<ForestTile> = Grid::load(lines); | |
| let slopes = [(1,1),(3,1),(5,1),(7,1),(1,2)]; | |
| let num_trees: Vec<usize> = slopes.iter().map(|(col_step,row_step)| -> usize { | |
| (0..grid.rows) | |
| .step_by(*row_step) | |
| .enumerate() | |
| .filter(|(col_index,row)| -> bool { | |
| grid[&Position { row: *row, column: (col_index * col_step) % grid.cols }] == ForestTile::Tree | |
| }) | |
| .count() | |
| }).collect(); | |
| let p2: usize = num_trees.iter().product(); | |
| Solution { part_1: num_trees[1].to_string(), part_2: p2.to_string() } | |
| } |
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