80 lines
2.1 KiB
Rust
80 lines
2.1 KiB
Rust
// Copyright 2022 Christian Ulrich
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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use std::io;
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pub struct Forest {
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trees: Vec<Vec<u8>>,
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}
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pub enum Direction {
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North,
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East,
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South,
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West,
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}
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pub struct Trees<'a> {
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forest: &'a Forest,
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direction: Direction,
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x: usize,
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y: usize,
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}
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impl Forest {
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pub fn from_stdin() -> Result<Forest, &'static str> {
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let mut trees = vec![];
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for line in io::stdin().lines() {
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let line = line.unwrap();
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if line.len() > 0 {
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trees.push(line.bytes().map(|b| b - '0' as u8).collect());
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}
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}
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Ok(Self { trees: trees })
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}
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pub fn dimensions(&self) -> (usize, usize) {
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(self.trees[0].len(), self.trees.len())
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}
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pub fn tree(&self, x: usize, y: usize) -> Option<u8> {
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Some(*self.trees.get(y)?.get(x)?)
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}
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pub fn view(&self, x: usize, y: usize, direction: Direction) -> Option<Trees> {
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let _ = self.tree(x, y)?;
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Some(Trees {
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forest: self,
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direction: direction,
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x: x,
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y: y,
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})
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}
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}
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impl Iterator for Trees<'_> {
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type Item = u8;
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fn next(&mut self) -> Option<Self::Item> {
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match self.direction {
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Direction::North => self.y = self.y.checked_sub(1)?,
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Direction::East => self.x = self.x.checked_add(1)?,
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Direction::South => self.y = self.y.checked_add(1)?,
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Direction::West => self.x = self.x.checked_sub(1)?,
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};
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self.forest.tree(self.x, self.y)
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}
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}
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