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extern crate advent_of_code_2018;
use advent_of_code_2018::*;
use std::error::Error;
use std::path::PathBuf;
use std::u32;
use std::collections::{HashMap, HashSet};
// cargo watch -cs "cargo run --release --bin day_22"
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
struct Position {
x: u32,
y: u32,
equipment: u32 // 0 = nothing, 1 = torch, 2 = climbing
}
impl Position {
fn adjacent(&self, map: &Vec<Vec<u32>>) -> Vec<(Position, u32)> {
let all_adjacent = [
(Position {
x: self.x.saturating_sub(1),
..*self
}, 1),
(Position {
y: self.y.saturating_sub(1),
..*self
}, 1),
(Position {
x: self.x+1,
..*self
}, 1),
(Position {
y: self.y+1,
..*self
}, 1),
(Position {
equipment: (self.equipment+1)%3,
..*self
}, 7),
(Position {
equipment: (self.equipment+2)%3,
..*self
}, 7)
];
all_adjacent.iter()
.filter(|(p, _)| {
let region = map[p.y as usize][p.x as usize];
let out_of_bounds = self == p;
let invalid_equipment = (region == 0 && p.equipment == 0) ||
(region == 1 && p.equipment == 1) ||
(region == 2 && p.equipment == 2);
!out_of_bounds && !invalid_equipment
})
.cloned()
.collect()
}
}
fn main() -> Result<(), Box<Error>> {
let input = &read_file(&PathBuf::from("inputs/22.txt"))?;
let depth: u32 = input[0].trim_matches(|c: char| !c.is_numeric()).parse().unwrap();
debug!(depth);
let mut input_target_iter = input[1]
.split(|c: char| !c.is_numeric())
.filter(|s| !s.is_empty())
.map(|s| s.parse::<u32>().unwrap());
let target_x = input_target_iter.next().unwrap();
let target_y = input_target_iter.next().unwrap();
debug!((target_x, target_y));
let mut map_width = target_x;
let mut map_height = target_y;
let mut map = build_map(map_width, map_height, depth, target_x, target_y);
let risk: u32 = map.iter().take((target_y+1) as usize).map(|row| row.iter().take((target_x+1) as usize).sum::<u32>()).sum();
debug!(risk);
let mut distances = HashMap::new();
let mut unexplored = HashSet::new();
let initial = Position {
x: 0,
y: 0,
equipment: 1
};
let target = Position {
x: target_x,
y: target_y,
equipment: 1
};
distances.insert(initial, 0);
unexplored.insert(initial);
while !distances.contains_key(&target) || unexplored.contains(&target) {
let (current, current_distance) = unexplored.iter()
.map(|unexp| (unexp.clone(), distances.get(unexp).cloned().unwrap()))
.min_by_key(|(_, d)| *d)
.unwrap();
if current.y+1 >= map_height {
map_height *= 2;
map = build_map(map_width, map_height, depth, target_x, target_y);
debug!(map_height);
}
if current.x+1 >= map_width {
map_width *= 2;
map = build_map(map_width, map_height, depth, target_x, target_y);
debug!(map_width);
}
for (adjacent, further) in current.adjacent(&map) {
let distance = current_distance + further;
let best_previous_distance = distances.get(&adjacent).cloned().unwrap_or(u32::MAX);
if best_previous_distance > distance {
distances.insert(adjacent, distance);
unexplored.insert(adjacent);
}
}
unexplored.remove(¤t);
}
debug!(distances.get(&target));
Ok(())
}
fn build_map(max_x: u32, max_y: u32, depth: u32, target_x: u32, target_y: u32) -> Vec<Vec<u32>> {
let mut geologic_index: Vec<Vec<u32>> = Vec::new();
let mut erosion_level: Vec<Vec<u32>> = Vec::new();
let mut region_type: Vec<Vec<u32>> = Vec::new();
for y in 0..max_y {
let mut geologic_row = Vec::new();
let mut erosion_row = Vec::new();
let mut type_row = Vec::new();
for x in 0..max_x {
let index = match (x, y) {
(0, 0) => 0,
(x, y) if x == target_x && y == target_y => 0,
(x, 0) => x*16807,
(0, y) => y*48271,
(x, y) => erosion_row[(x-1) as usize] * erosion_level[(y-1) as usize][x as usize]
};
let erosion = (index + depth) % 20183;
let block_type = erosion % 3;
geologic_row.push(index);
erosion_row.push(erosion);
type_row.push(block_type);
}
geologic_index.push(geologic_row);
erosion_level.push(erosion_row);
region_type.push(type_row);
}
region_type
}
|
