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advent-of-code-2022/day8/src/main.rs

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use std::collections::HashSet;
#[derive(Debug, Copy, Clone, PartialOrd, PartialEq, Eq, Hash)]
enum VisibleDirection {
Top,
Bottom,
Left,
Right,
}
use VisibleDirection::*;
#[derive(Debug, Default)]
struct Tree {
height: usize,
visible: HashSet<VisibleDirection>,
}
impl Tree {
fn new(height: usize) -> Self {
Tree {
height,
..Tree::default()
}
}
fn is_visible(&self) -> bool {
!self.visible.is_empty()
}
fn set_visible(&mut self, dir: VisibleDirection) -> &mut Self {
self.visible.insert(dir);
self
}
fn set_all_visible(&mut self) -> &mut Self {
self.set_visible(Top)
.set_visible(Bottom)
.set_visible(Left)
.set_visible(Right)
}
}
// ----------------------------------------------------------------------------
#[derive(Debug)]
struct Grid<T> {
width: usize,
vec: Vec<T>,
}
impl<T> Grid<T> {
fn new(width: usize) -> Self {
Grid {
width,
vec: Vec::new(),
}
}
// Convert x,y coordinate into linear array index
fn xy_idx(&self, x: usize, y: usize) -> usize {
(y * self.width) + x
}
/// Convert linear array index to x,y coordinate
fn idx_xy(&self, idx: usize) -> (usize, usize) {
(idx % self.width, idx / self.width)
}
fn row_first_idx(&self, row: usize) -> usize {
let idx = row * self.width;
if idx < self.vec.len() {
idx
} else {
self.vec.len()
}
}
fn row_last_idx(&self, row: usize) -> usize {
if (row + 1) > self.num_rows() {
return self.vec.len();
}
self.row_first_idx(row + 1) - 1
}
fn num_rows(&self) -> usize {
let even_rows = self.vec.len() / self.width;
if self.vec.len() % self.width > 0 {
even_rows + 1
} else {
even_rows
}
}
fn num_cols(&self) -> usize {
self.width
}
fn get_row(&mut self, row_num: usize) -> &mut [T] {
let start = self.row_first_idx(row_num);
let end = self.row_last_idx(row_num);
&mut self.vec[start..=end]
}
fn get_column_indexes(&self, col_num: usize) -> Vec<usize> {
let mut indexes = Vec::new();
if col_num > self.num_cols() {
return indexes;
}
for r in 0..self.num_rows() {
let idx = self.width * r + col_num;
indexes.push(idx);
}
indexes
}
}
impl Grid<Tree> {
fn mark_outer_trees_visible(&mut self) {
fn set_row_visible(row: &mut [Tree]) {
row.iter_mut().for_each(|tree| { tree.set_all_visible(); })
}
// Set top/bottom rows as visible
set_row_visible(self.get_row(0));
set_row_visible(self.get_row(self.num_rows() - 1));
// Set left/right cols as visible
self.get_column_indexes(0).into_iter().for_each(|id| {
self.vec[id].set_all_visible();
});
self.get_column_indexes(self.num_cols() - 1).into_iter().for_each(|id| {
self.vec[id].set_all_visible();
});
}
fn mark_visible_trees(&mut self) {
self.mark_outer_trees_visible();
}
pub fn get_visible_trees(&self) -> usize {
self
.vec
.iter()
.filter(|tree| tree.is_visible())
.collect::<Vec<&Tree>>()
.len()
}
fn from_file_str(file_str: &'static str) -> Grid<Tree> {
let lines: Vec<&str> = file_str.lines().collect();
let width = lines[0].len();
let mut grid: Grid<Tree> = Grid::new(width);
for line in lines {
let mut row: Vec<Tree> = line
.chars()
.map(|ch| Tree::new(ch.to_digit(10).unwrap() as usize))
.collect();
grid.vec.append(&mut row);
}
grid
}
}
// ----------------------------------------------------------------------------
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fn main() {
let file_str = include_str!("input.txt");
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let mut grid = Grid::from_file_str(file_str);
grid.mark_visible_trees();
let visible_num = grid.get_visible_trees();
println!("Part 1: Number of visible trees: {}", visible_num);
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}
#[cfg(test)]
mod tests {
use super::*;
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fn get_data() -> &'static str {
include_str!("test-input.txt")
}
#[test]
fn test_outer_visible_trees() {
let mut grid = Grid::from_file_str(get_data());
grid.mark_outer_trees_visible();
assert_eq!(grid.get_visible_trees(), 16usize);
}
}