diff options
| -rw-r--r-- | src/day5.rs | 133 |
1 files changed, 130 insertions, 3 deletions
diff --git a/src/day5.rs b/src/day5.rs index 9e1a49e..e2dd830 100644 --- a/src/day5.rs +++ b/src/day5.rs @@ -126,6 +126,114 @@ impl TryFrom<&Line> for AxisAlignedLine { } } +#[derive(Debug)] +struct DiagonalLine { + start : Point, + length : usize, + y_negative : bool, +} + +#[derive(Debug)] +enum AlignedLine { + AxisAligned(AxisAlignedLine), + Diagonal(DiagonalLine), +} + +#[derive(Debug)] +struct NotAlignedError; +impl Display for NotAlignedError { + fn fmt(&self, f : &mut Formatter) -> Result<(), std::fmt::Error> { + write!(f, "Line neither axis aligned nor 45° diagonal, cannot be converted to AlignedLine") + } +} +impl Error for NotAlignedError {} + +impl TryFrom<&Line> for AlignedLine { + type Error = NotAlignedError; + fn try_from(line : &Line) -> Result<Self, NotAlignedError> { + use std::cmp::{min,max}; + if let Ok(axis_aligned) = line.try_into() { + Ok(Self::AxisAligned(axis_aligned)) + } + else { + let min_x = min(line.endpoints[0].x, line.endpoints[1].x); + let max_x = max(line.endpoints[0].x, line.endpoints[1].x); + let min_y = min(line.endpoints[0].y, line.endpoints[1].y); + let max_y = max(line.endpoints[0].y, line.endpoints[1].y); + if max_y - min_y == max_x - min_x { + let start_index = if line.endpoints[0].x < line.endpoints[1].x { 0 } else { 1 }; + Ok(Self::Diagonal(DiagonalLine { + start : Point { x: line.endpoints[start_index].x, y: line.endpoints[start_index].y}, + length : max_y-min_y, + y_negative : line.endpoints[1-start_index].y < line.endpoints[start_index].y, + })) + } + else { + Err(NotAlignedError) + } + } + } +} + +impl AlignedLine { + fn iter(&self) -> AlignedLineIterator<&DiagonalLine, &AxisAlignedLine> { + match self { + AlignedLine::AxisAligned(axis_aligned_line) => { + AlignedLineIterator::Aligned(axis_aligned_line.iter()) + } + AlignedLine::Diagonal(line) => { + AlignedLineIterator::Diagonal { line, index : 0 } + } + } + } + fn into_iter(self) -> AlignedLineIterator<DiagonalLine, AxisAlignedLine> { + match self { + AlignedLine::AxisAligned(axis_aligned_line) => { + AlignedLineIterator::Aligned(axis_aligned_line.into_iter()) + } + AlignedLine::Diagonal(line) => { + AlignedLineIterator::Diagonal { line, index : 0 } + } + } + } +} + +enum AlignedLineIterator<T, Q> + where T: Borrow<DiagonalLine>, + Q: Borrow<AxisAlignedLine> +{ + Aligned(AxisAlignedLineIterator<Q>), + Diagonal { + line : T, + index : usize, + } +} + +impl<T,Q> Iterator for AlignedLineIterator<T,Q> + where T: Borrow<DiagonalLine>, + Q: Borrow<AxisAlignedLine> +{ + type Item = Point; + fn next(&mut self) -> Option<Point> { + match self { + AlignedLineIterator::Aligned(aligned_iterator) => { aligned_iterator.next() } + AlignedLineIterator::Diagonal { line, index : self_index } => { + let index = *self_index; + let line = (*line).borrow(); + if index <= line.length { + *self_index += 1; + Some(Point { + x: line.start.x + index, + y: if line.y_negative { line.start.y - index } else { line.start.y + index } + }) + } + else { + None + } + } + } + } +} #[derive(Debug)] pub enum LineParsingError { @@ -200,17 +308,31 @@ pub fn input_generator(input : &str) -> Result<Vec<Line>, LineParsingError> { ) } -#[aoc(day5, part1, Plotted)] -pub fn solve_day5_part1_plotted(lines : &Vec<Line>) -> usize { +fn solve_day5_with_map<'a, T,Q,I>(lines : &'a Vec<Line>, map : T) -> usize + where T : Fn(Q)-> I, + I : Iterator<Item=Point>, + Q : TryFrom<&'a Line> +{ use std::collections::hash_map::HashMap as Map; let hit_locations = lines.iter() .filter_map(|line| line.try_into().ok()) - .flat_map(|axis_aligned_line : AxisAlignedLine| axis_aligned_line.into_iter()); + .flat_map(map); let hit_counts = hit_locations.fold(Map::new(), |mut map, point| { map.entry(point).and_modify(|x| *x+=1).or_insert(1); map }); hit_counts.iter().filter(|(_, value)| **value >= 2).count() + +} + +#[aoc(day5, part1, Plotted)] +pub fn solve_day5_part1_plotted(lines : &Vec<Line>) -> usize { + solve_day5_with_map(lines, |axis_aligned_line : AxisAlignedLine| axis_aligned_line.into_iter()) +} + +#[aoc(day5, part2, Plotted)] +pub fn solve_day5_part2_plotted(lines : &Vec<Line>) -> usize { + solve_day5_with_map(lines, |aligned_line : AlignedLine| aligned_line.into_iter()) } #[cfg(test)] @@ -256,4 +378,9 @@ r#"0,9 -> 5,9 assert_eq!(solve_day5_part1_plotted(&get_day5_parsed_testdata()), 5) } + #[test] + fn test_day5_part2_solution_plotted() { + assert_eq!(solve_day5_part2_plotted(&get_day5_parsed_testdata()), 12) + } + } |