2022 - Day 23

2022/input/23/input

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2022/input/23/test-1

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+.....
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+.....
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+.....

2022/input/23/test-2

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+....#..
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2022/src/bin/day23.rs

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+#![feature(test)]
+use std::{collections::HashMap, str::FromStr};
+
+use anyhow::Result;
+use aoc::Solver;
+
+// -- Runners --
+fn main() -> Result<()> {
+    Day::solve()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_test1() -> Result<()> {
+        Day::test(Day::part1, "test-1", 25)
+    }
+    #[test]
+    fn part1_test2() -> Result<()> {
+        Day::test(Day::part1, "test-2", 110)
+    }
+    #[test]
+    fn part1_solution() -> Result<()> {
+        Day::test(Day::part1, "input", 3849)
+    }
+    #[test]
+    fn part2_test1() -> Result<()> {
+        Day::test(Day::part2, "test-1", 4)
+    }
+    #[test]
+    fn part2_test2() -> Result<()> {
+        Day::test(Day::part2, "test-2", 20)
+    }
+
+    // Benchmarks
+    extern crate test;
+    #[bench]
+    #[ignore]
+    fn part1_bench(b: &mut test::Bencher) {
+        Day::benchmark(Day::part1, b)
+    }
+    #[bench]
+    #[ignore]
+    fn part2_bench(b: &mut test::Bencher) {
+        Day::benchmark(Day::part2, b)
+    }
+}
+
+#[derive(Debug, Hash, PartialEq, Eq, Copy, Clone)]
+struct Vec2 {
+    x: isize,
+    y: isize,
+}
+
+impl Vec2 {
+    fn new(x: isize, y: isize) -> Self {
+        Self { x, y }
+    }
+
+    fn offset(&self, other: &Vec2) -> Self {
+        Self { x: self.x+other.x, y: self.y+other.y }
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+struct Elf {
+    considering: Vec2,
+    offset: usize,
+}
+
+impl Elf {
+    fn new() -> Self {
+        Self { considering: Vec2::new(0, 0), offset: 0 }
+    }
+}
+
+#[derive(Debug)]
+struct Map {
+    elves: HashMap<Vec2, Elf>,
+    considered: HashMap<Vec2, usize>,
+}
+
+impl FromStr for Map {
+    type Err = anyhow::Error;
+
+    fn from_str(input: &str) -> Result<Self, Self::Err> {
+        let elves = input
+            .lines()
+            .enumerate()
+            .flat_map(|(y, line)| {
+                line
+                    .chars()
+                    .enumerate()
+                    .filter(|(_, c)| *c == '#')
+                    .map(move |(x, _)| {
+                        (Vec2::new(x as isize, y as isize), Elf::new())
+                    })
+            }).collect();
+
+        Ok(Self { elves, considered: HashMap::new()})
+    }
+}
+
+impl Map {
+    fn consider(&mut self) {
+        let north = ([Vec2::new(-1, -1), Vec2::new(0, -1), Vec2::new(1, -1)], Vec2::new(0, -1));
+        let south = ([Vec2::new(-1, 1), Vec2::new(0, 1), Vec2::new(1, 1)], Vec2::new(0, 1));
+        let west = ([Vec2::new(-1, -1), Vec2::new(-1, 0), Vec2::new(-1, 1)], Vec2::new(-1, 0));
+        let east = ([Vec2::new(1, -1), Vec2::new(1, 0), Vec2::new(1, 1)], Vec2::new(1, 0));
+
+        let moves = [north, south, west, east];
+
+        for (pos, elf) in self.elves.clone() {
+            // Default action is to stay in place
+            let mut next = pos;
+
+            if self.need_to_move(&pos) {
+                for m in moves.iter().cycle().skip(elf.offset).take(4) {
+                    if !self.occupied(pos.offset(&m.0[0])) && !self.occupied(pos.offset(&m.0[1])) && !self.occupied(pos.offset(&m.0[2])) {
+                        next = pos.offset(&m.1);
+                        break;
+                    }
+                }
+            }
+
+            // The offset is updated every round for all elves
+            self.elves.get_mut(&pos).unwrap().offset += 1;
+
+            // Set the position that the elf is considering
+            self.elves.get_mut(&pos).unwrap().considering = next;
+
+            // Increment counter for that position
+            *self.considered.entry(next).or_default() += 1;
+        }
+    }
+
+    fn occupied(&self, pos: Vec2) -> bool {
+        self.elves.contains_key(&pos)
+    }
+
+    fn need_to_move(&self, pos: &Vec2) -> bool {
+        for y in -1..2 {
+            for x in -1..2 {
+                if x == 0 && y == 0 {
+                    continue;
+                }
+
+                if self.elves.contains_key(&pos.offset(&Vec2::new(x, y))) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    fn make_moves(&mut self) -> bool {
+        // New hashmap that is going to contain the updated values
+        let mut elves = HashMap::new();
+
+        let mut moved = false;
+
+        for (pos, elf) in &self.elves {
+            if *self.considered.get(&elf.considering).unwrap() == 1 {
+                if elf.considering.x != pos.x || elf.considering.y != pos.y {
+                    moved = true;
+                }
+                // If only one elf is considering the new location, insert the elf into the new
+                // HashMap at the new location
+                elves.insert(elf.considering, *elf);
+            } else {
+                // Otherwise the elf will not move and stay at its old position
+                elves.insert(*pos, *elf);
+            }
+        }
+
+        // Update the hashmap
+        self.elves = elves;
+        // Clear the map tracking considered moves
+        self.considered.clear();
+
+        return moved;
+    }
+
+    fn get_size(&self) -> (Vec2, Vec2) {
+        let mut min = Vec2::new(isize::MAX, isize::MAX);
+        let mut max = Vec2::new(0, 0);
+
+        for pos in self.elves.keys() {
+            min.x = min.x.min(pos.x);
+            min.y = min.y.min(pos.y);
+
+            max.x = max.x.max(pos.x+1);
+            max.y = max.y.max(pos.y+1);
+        }
+
+        (min, max)
+    }
+
+    fn empty_tiles(&self) -> isize {
+        let (min, max) = self.get_size();
+        (max.x - min.x) * (max.y - min.y) - self.elves.len() as isize
+    }
+
+    fn print(&self) {
+        let (min, max) = self.get_size();
+        for y in min.y..max.y {
+            for x in min.x..max.x {
+                if self.elves.contains_key(&Vec2::new(x, y)) {
+                    print!("#");
+                } else {
+                    print!(".");
+                }
+            }
+            println!("");
+        }
+        println!("");
+    }
+}
+
+// -- Solution --
+pub struct Day;
+impl aoc::Solver for Day {
+    type Output1 = isize;
+    type Output2 = isize;
+
+    fn day() -> u8 {
+        23
+    }
+
+    fn part1(input: &str) -> Self::Output1 {
+        let mut map = Map::from_str(input).unwrap();
+
+        for _ in 0..10 {
+            map.consider();
+            map.make_moves();
+        }
+
+        map.empty_tiles()
+    }
+
+    fn part2(input: &str) -> Self::Output2 {
+        let mut map = Map::from_str(input).unwrap();
+
+        let mut counter = 0;
+        loop {
+            counter += 1;
+
+            map.consider();
+            if !map.make_moves() {
+                return counter;
+            }
+        }
+    }
+}