From 0b0f5f48388e16d96aa7e416fa50423d3ba5d52b Mon Sep 17 00:00:00 2001
From: pareronia <49491686+pareronia@users.noreply.github.com>
Date: Thu, 19 Dec 2024 19:40:36 +0100
Subject: [PATCH] AoC 2024 Day 12 - rust

---
 README.md                            |   2 +-
 src/main/rust/AoC2024_12/Cargo.toml  |   8 +
 src/main/rust/AoC2024_12/src/main.rs | 261 +++++++++++++++++++++++++++
 src/main/rust/Cargo.lock             |   8 +
 4 files changed, 278 insertions(+), 1 deletion(-)
 create mode 100644 src/main/rust/AoC2024_12/Cargo.toml
 create mode 100644 src/main/rust/AoC2024_12/src/main.rs

diff --git a/README.md b/README.md
index 30638db..6e14fee 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2024_01.py) | [✓](src/main/python/AoC2024_02.py) | [✓](src/main/python/AoC2024_03.py) | [✓](src/main/python/AoC2024_04.py) | [✓](src/main/python/AoC2024_05.py) | [✓](src/main/python/AoC2024_06.py) | [✓](src/main/python/AoC2024_07.py) | [✓](src/main/python/AoC2024_08.py) | [✓](src/main/python/AoC2024_09.py) | [✓](src/main/python/AoC2024_10.py) | [✓](src/main/python/AoC2024_11.py) | [✓](src/main/python/AoC2024_12.py) | [✓](src/main/python/AoC2024_13.py) | [✓](src/main/python/AoC2024_14.py) | [✓](src/main/python/AoC2024_15.py) | [✓](src/main/python/AoC2024_16.py) | [✓](src/main/python/AoC2024_17.py) | [✓](src/main/python/AoC2024_18.py) | [✓](src/main/python/AoC2024_19.py) |  |  |  |  |  |  |
 | java | [✓](src/main/java/AoC2024_01.java) | [✓](src/main/java/AoC2024_02.java) | [✓](src/main/java/AoC2024_03.java) | [✓](src/main/java/AoC2024_04.java) | [✓](src/main/java/AoC2024_05.java) | [✓](src/main/java/AoC2024_06.java) | [✓](src/main/java/AoC2024_07.java) | [✓](src/main/java/AoC2024_08.java) |  | [✓](src/main/java/AoC2024_10.java) | [✓](src/main/java/AoC2024_11.java) | [✓](src/main/java/AoC2024_12.java) |  | [✓](src/main/java/AoC2024_14.java) | [✓](src/main/java/AoC2024_15.java) |  |  |  |  |  |  |  |  |  |  |
-| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) | [✓](src/main/rust/AoC2024_07/src/main.rs) | [✓](src/main/rust/AoC2024_08/src/main.rs) |  | [✓](src/main/rust/AoC2024_10/src/main.rs) | [✓](src/main/rust/AoC2024_11/src/main.rs) |  | [✓](src/main/rust/AoC2024_13/src/main.rs) | [✓](src/main/rust/AoC2024_14/src/main.rs) | [✓](src/main/rust/AoC2024_15/src/main.rs) | [✓](src/main/rust/AoC2024_16/src/main.rs) | [✓](src/main/rust/AoC2024_17/src/main.rs) | [✓](src/main/rust/AoC2024_18/src/main.rs) |  |  |  |  |  |  |  |
+| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) | [✓](src/main/rust/AoC2024_07/src/main.rs) | [✓](src/main/rust/AoC2024_08/src/main.rs) |  | [✓](src/main/rust/AoC2024_10/src/main.rs) | [✓](src/main/rust/AoC2024_11/src/main.rs) | [✓](src/main/rust/AoC2024_12/src/main.rs) | [✓](src/main/rust/AoC2024_13/src/main.rs) | [✓](src/main/rust/AoC2024_14/src/main.rs) | [✓](src/main/rust/AoC2024_15/src/main.rs) | [✓](src/main/rust/AoC2024_16/src/main.rs) | [✓](src/main/rust/AoC2024_17/src/main.rs) | [✓](src/main/rust/AoC2024_18/src/main.rs) |  |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2024@ -->
 
 ## 2023
diff --git a/src/main/rust/AoC2024_12/Cargo.toml b/src/main/rust/AoC2024_12/Cargo.toml
new file mode 100644
index 0000000..c07e778
--- /dev/null
+++ b/src/main/rust/AoC2024_12/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "AoC2024_12"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }
+itertools = "0.11"
diff --git a/src/main/rust/AoC2024_12/src/main.rs b/src/main/rust/AoC2024_12/src/main.rs
new file mode 100644
index 0000000..c9ead4f
--- /dev/null
+++ b/src/main/rust/AoC2024_12/src/main.rs
@@ -0,0 +1,261 @@
+#![allow(non_snake_case)]
+
+use aoc::geometry::Direction;
+use aoc::graph::BFS;
+use aoc::grid::Cell;
+use aoc::Puzzle;
+use itertools::Itertools;
+use std::collections::{HashMap, HashSet};
+
+#[derive(Clone, Debug)]
+struct Regions {
+    plots_by_plant: HashMap<char, HashSet<Cell>>,
+}
+
+impl Regions {
+    fn new() -> Self {
+        Self {
+            plots_by_plant: HashMap::new(),
+        }
+    }
+
+    fn iter(&self) -> RegionIterator {
+        RegionIterator {
+            all_plots_with_plant: self.plots_by_plant.values().collect(),
+            index: 0,
+            seen: HashSet::new(),
+        }
+    }
+}
+
+impl FromIterator<(char, Cell)> for Regions {
+    fn from_iter<I: IntoIterator<Item = (char, Cell)>>(iter: I) -> Self {
+        let mut regions = Regions::new();
+        for (ch, cell) in iter {
+            regions
+                .plots_by_plant
+                .entry(ch)
+                .and_modify(|s| {
+                    s.insert(cell);
+                })
+                .or_insert(HashSet::from([cell]));
+        }
+        regions
+    }
+}
+
+struct RegionIterator<'a> {
+    all_plots_with_plant: Vec<&'a HashSet<Cell>>,
+    index: usize,
+    seen: HashSet<Cell>,
+}
+
+#[allow(clippy::needless_lifetimes)]
+impl<'a> Iterator for RegionIterator<'a> {
+    type Item = HashSet<Cell>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.seen.len() == self.all_plots_with_plant[self.index].len() {
+            if self.index + 1 == self.all_plots_with_plant.len() {
+                return None;
+            }
+            self.index += 1;
+            self.seen.clear();
+        }
+        let region = BFS::flood_fill(
+            *self.all_plots_with_plant[self.index]
+                .difference(&self.seen)
+                .next()
+                .unwrap(),
+            |cell| {
+                cell.capital_neighbours()
+                    .into_iter()
+                    .filter(|n| {
+                        self.all_plots_with_plant[self.index].contains(n)
+                            && !self.seen.contains(n)
+                    })
+                    .collect()
+            },
+        );
+        region.iter().for_each(|r| {
+            self.seen.insert(*r);
+        });
+        Some(region)
+    }
+}
+
+struct AoC2024_12;
+
+impl AoC2024_12 {
+    fn solve<F>(&self, input: &[String], count: F) -> usize
+    where
+        F: Fn(&Cell, &HashSet<Cell>) -> usize,
+    {
+        let regions: Regions = (0..input.len())
+            .cartesian_product(0..input[0].len())
+            .map(|(r, c)| (input[r].chars().nth(c).unwrap(), Cell::at(r, c)))
+            .collect();
+        regions
+            .iter()
+            .map(|r| {
+                r.iter()
+                    .map(|plot| count(plot, &r) * r.len())
+                    .sum::<usize>()
+            })
+            .sum()
+    }
+}
+
+impl aoc::Puzzle for AoC2024_12 {
+    type Input = Vec<String>;
+    type Output1 = usize;
+    type Output2 = usize;
+
+    aoc::puzzle_year_day!(2024, 12);
+
+    fn parse_input(&self, lines: Vec<String>) -> Self::Input {
+        lines
+    }
+
+    fn part_1(&self, input: &Self::Input) -> Self::Output1 {
+        let count_edges = |plot: &Cell, region: &HashSet<Cell>| {
+            4 - plot
+                .capital_neighbours()
+                .iter()
+                .filter(|n| region.contains(n))
+                .count()
+        };
+        self.solve(input, count_edges)
+    }
+
+    fn part_2(&self, input: &Self::Input) -> Self::Output2 {
+        let corner_dirs = [
+            [Direction::LeftAndUp, Direction::Left, Direction::Up],
+            [Direction::RightAndUp, Direction::Right, Direction::Up],
+            [Direction::RightAndDown, Direction::Right, Direction::Down],
+            [Direction::LeftAndDown, Direction::Left, Direction::Down],
+        ];
+        let matches = [
+            [false, false, false],
+            [true, false, false],
+            [false, true, true],
+        ];
+        let count_corners = |plot: &Cell, region: &HashSet<Cell>| {
+            corner_dirs
+                .iter()
+                .filter(|d| {
+                    let test = (0..3)
+                        .map(|i| match plot.try_at(d[i]) {
+                            Some(n) => region.contains(&n),
+                            None => false,
+                        })
+                        .collect::<Vec<bool>>();
+                    matches.iter().any(|m| *m == *test)
+                })
+                .count()
+        };
+        self.solve(input, count_corners)
+    }
+
+    fn samples(&self) {
+        aoc::puzzle_samples! {
+            self, part_1, TEST1, 140,
+            self, part_1, TEST2, 772,
+            self, part_1, TEST3, 1930,
+            self, part_2, TEST1, 80,
+            self, part_2, TEST2, 436,
+            self, part_2, TEST3, 1206,
+            self, part_2, TEST4, 236,
+            self, part_2, TEST5, 368
+        };
+    }
+}
+
+fn main() {
+    AoC2024_12 {}.run(std::env::args());
+}
+
+const TEST1: &str = "\
+AAAA
+BBCD
+BBCC
+EEEC
+";
+const TEST2: &str = "\
+OOOOO
+OXOXO
+OOOOO
+OXOXO
+OOOOO
+";
+const TEST3: &str = "\
+RRRRIICCFF
+RRRRIICCCF
+VVRRRCCFFF
+VVRCCCJFFF
+VVVVCJJCFE
+VVIVCCJJEE
+VVIIICJJEE
+MIIIIIJJEE
+MIIISIJEEE
+MMMISSJEEE
+";
+const TEST4: &str = "\
+EEEEE
+EXXXX
+EEEEE
+EXXXX
+EEEEE
+";
+const TEST5: &str = "\
+AAAAAA
+AAABBA
+AAABBA
+ABBAAA
+ABBAAA
+AAAAAA
+";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn samples() {
+        AoC2024_12 {}.samples();
+    }
+
+    #[test]
+    pub fn regions_iterator() {
+        // AABBC
+        // ACCDC
+        let regions: Regions = [
+            ('A', Cell::at(0, 0)),
+            ('A', Cell::at(0, 1)),
+            ('B', Cell::at(0, 2)),
+            ('B', Cell::at(0, 3)),
+            ('C', Cell::at(0, 4)),
+            ('A', Cell::at(1, 0)),
+            ('C', Cell::at(1, 1)),
+            ('C', Cell::at(1, 2)),
+            ('D', Cell::at(1, 3)),
+            ('C', Cell::at(1, 4)),
+        ]
+        .into_iter()
+        .collect();
+        let ans = regions.iter().collect::<Vec<_>>();
+        // A
+        assert!(ans.contains(&HashSet::from([
+            Cell::at(0, 0),
+            Cell::at(0, 1),
+            Cell::at(1, 0),
+        ])));
+        // B
+        assert!(ans.contains(&HashSet::from([Cell::at(0, 2), Cell::at(0, 3),])));
+        // C
+        assert!(ans.contains(&HashSet::from([Cell::at(0, 4), Cell::at(1, 4),])));
+        assert!(ans.contains(&HashSet::from([Cell::at(1, 1), Cell::at(1, 2),])));
+        // D
+        assert!(ans.contains(&HashSet::from([Cell::at(1, 3)])));
+    }
+}
diff --git a/src/main/rust/Cargo.lock b/src/main/rust/Cargo.lock
index 6fae952..bdd4915 100644
--- a/src/main/rust/Cargo.lock
+++ b/src/main/rust/Cargo.lock
@@ -464,6 +464,14 @@ dependencies = [
  "cached",
 ]
 
+[[package]]
+name = "AoC2024_12"
+version = "0.1.0"
+dependencies = [
+ "aoc",
+ "itertools",
+]
+
 [[package]]
 name = "AoC2024_13"
 version = "0.1.0"