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Part 1 of Day 10

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Adam Wick
2019-12-24 10:44:11 -08:00
parent c94526ef3e
commit ad13523d00
3 changed files with 190 additions and 0 deletions
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inputs/day10 Normal file
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#..#....#...#.#..#.......##.#.####
#......#..#.#..####.....#..#...##.
.##.......#..#.#....#.#..#.#....#.
###..#.....###.#....##.....#...#..
...#.##..#.###.......#....#....###
.####...##...........##..#..#.##..
..#...#.#.#.###....#.#...##.....#.
......#.....#..#...##.#..##.#..###
...###.#....#..##.#.#.#....#...###
..#.###.####..###.#.##..#.##.###..
...##...#.#..##.#............##.##
....#.##.##.##..#......##.........
.#..#.#..#.##......##...#.#.#...##
.##.....#.#.##...#.#.#...#..###...
#.#.#..##......#...#...#.......#..
#.......#..#####.###.#..#..#.#.#..
.#......##......##...#..#..#..###.
#.#...#..#....##.#....#.##.#....#.
....#..#....##..#...##..#..#.#.##.
#.#.#.#.##.#.#..###.......#....###
...#.#..##....###.####.#..#.#..#..
#....##..#...##.#.#.........##.#..
.#....#.#...#.#.........#..#......
...#..###...#...#.#.#...#.#..##.##
.####.##.#..#.#.#.#...#.##......#.
.##....##..#.#.#.......#.....####.
#.##.##....#...#..#.#..###..#.###.
...###.#..#.....#.#.#.#....#....#.
......#...#.........##....#....##.
.....#.....#..#.##.#.###.#..##....
.#.....#.#.....#####.....##..#....
.####.##...#.......####..#....##..
.#.#.......#......#.##..##.#.#..##
......##.....##...##.##...##......

2
src/main.rs
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@@ -15,6 +15,8 @@ mod scaffold;
#[cfg(test)]
mod spring;
#[cfg(test)]
mod station;
#[cfg(test)]
mod tractor;
mod wiremap;

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src/station.rs Normal file
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use std::fs;
use std::str;
struct StationMap {
data: Vec<bool>,
width: usize,
height: usize,
}
impl StationMap {
fn new(encoding: &str) -> StationMap {
let mut data = vec![];
let mut width = 0;
let mut height = 0;
for c in encoding.chars() {
match c {
'.' => data.push(false),
'#' => data.push(true),
'\n' if width == 0 => {
width = data.len();
height = 1;
}
'\n' => height += 1,
_ => panic!("Unexpected character: {}", c),
}
}
StationMap{ data, width, height }
}
fn get(&self, x: usize, y: usize) -> bool {
self.data[ (y * self.width) + x ]
}
fn count_visible(&self, from_x: usize, from_y: usize) -> usize {
let mut count = 0;
for x in 0..self.width {
for y in 0..self.height {
if self.get(x, y) && ((x != from_x) || (y != from_y)) {
let diff_x = diff(x, from_x);
let diff_y = diff(y, from_y);
let gcd = gcd(diff_x, diff_y);
let rise = diff_y / gcd;
let run = diff_x / gcd;
let mut curx = from_x;
let mut cury = from_y;
let shadowed = loop {
let (newx, newy) = match (x > from_x, y > from_y) {
// we're going down and right
(true, true) => (curx + run, cury + rise),
// we're going up and right
(true, false) => (curx + run, cury - rise),
// we're going down and left
(false, true) => (curx - run, cury + rise),
// we're going up and left
(false, false) => (curx - run, cury - rise),
};
if newx == x && newy == y {
break false;
}
if self.get(newx, newy) {
break true;
}
curx = newx;
cury = newy;
};
if !shadowed {
count += 1;
}
}
}
}
count
}
fn place_station(&self) -> (usize, usize, usize) {
let mut most_found = 0;
let mut best_x = 0;
let mut best_y = 0;
for y in 0..self.height {
for x in 0..self.width {
if self.get(x, y) {
let mine = self.count_visible(x, y);
if mine > most_found {
best_x = x;
best_y = y;
most_found = mine;
}
}
}
}
(most_found, best_x, best_y)
}
fn print(&self) {
for y in 0..self.height {
for x in 0..self.width {
if self.get(x, y) {
print!("#");
} else {
print!(".");
}
}
println!();
}
}
}
fn diff(a: usize, b: usize) -> usize {
if a > b {
a - b
} else {
b - a
}
}
fn gcd(mut x: usize, mut y: usize) -> usize {
while y != 0 {
let t = x % y;
x = y;
y = t;
}
x
}
#[test]
fn day10() {
let example1 = StationMap::new(".#..#\n.....\n#####\n....#\n...##\n");
assert_eq!((8, 3, 4), example1.place_station());
let example2 = StationMap::new("......#.#.\n#..#.#....\n..#######.\n.#.#.###..\n.#..#.....\n..#....#.#\n#..#....#.\n.##.#..###\n##...#..#.\n.#....####\n");
assert_eq!((33,5,8), example2.place_station());
let example3 = StationMap::new("#.#...#.#.\n.###....#.\n.#....#...\n##.#.#.#.#\n....#.#.#.\n.##..###.#\n..#...##..\n..##....##\n......#...\n.####.###.\n");
assert_eq!((35,1,2), example3.place_station());
let example4 = StationMap::new(".#..#..###\n####.###.#\n....###.#.\n..###.##.#\n##.##.#.#.\n....###..#\n..#.#..#.#\n#..#.#.###\n.##...##.#\n.....#.#..\n");
assert_eq!((41,6,3), example4.place_station());
let example5 = StationMap::new(".#..##.###...#######\n##.############..##.\n.#.######.########.#\n.###.#######.####.#.\n#####.##.#.##.###.##\n..#####..#.#########\n####################\n#.####....###.#.#.##\n##.#################\n#####.##.###..####..\n..######..##.#######\n####.##.####...##..#\n.#####..#.######.###\n##...#.##########...\n#.##########.#######\n.####.#.###.###.#.##\n....##.##.###..#####\n.#.#.###########.###\n#.#.#.#####.####.###\n###.##.####.##.#..##\n");
assert_eq!((210,11,13), example5.place_station());
let day10_contents = fs::read("inputs/day10").expect("Couldn't open day10 problem");
let day10_str = str::from_utf8(&day10_contents).expect("Couldn't decode day10 problem");
let day10a = StationMap::new(&day10_str);
day10a.print();
assert_eq!((334,23,20), day10a.place_station());
}