From b93563d249cc8dcac7e645bea67d5645010804de Mon Sep 17 00:00:00 2001
From: Julius de Jeu <julius@voidcorp.nl>
Date: Sat, 11 Dec 2021 09:45:35 +0100
Subject: [PATCH] Day 11

---
 input/day11  |  10 ++++
 src/day11.rs | 145 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs  |   5 +-
 3 files changed, 159 insertions(+), 1 deletion(-)
 create mode 100644 input/day11
 create mode 100644 src/day11.rs

diff --git a/input/day11 b/input/day11
new file mode 100644
index 0000000..44e9f75
--- /dev/null
+++ b/input/day11
@@ -0,0 +1,10 @@
+2566885432
+3857414357
+6761543247
+5477332114
+3731585385
+1716783173
+1277321612
+3371176148
+1162578285
+6144726367
\ No newline at end of file
diff --git a/src/day11.rs b/src/day11.rs
new file mode 100644
index 0000000..9701fc6
--- /dev/null
+++ b/src/day11.rs
@@ -0,0 +1,145 @@
+use std::collections::HashMap;
+use crate::Day;
+
+type FlashMap = HashMap<(i32, i32), i32>;
+
+pub struct Day11(FlashMap);
+
+impl Day for Day11 {
+    fn init(content: String) -> anyhow::Result<Self> {
+        let mut map = HashMap::new();
+        for (y, n) in content.lines().enumerate() {
+            for (x, char) in n.chars().enumerate() {
+                map.insert((x as i32, y as i32), char.to_string().parse::<i32>()?);
+            }
+        }
+        Ok(Self(map))
+    }
+
+    fn part1(&self) -> anyhow::Result<String> {
+        let mut hm = self.0.clone();
+        let mut flashes = 0;
+        for _ in 0..100 {
+            hm.iter_mut().for_each(|(_, x)| *x += 1);
+            let mut flashing = get_flashes(&hm);
+            let mut flashed = vec![];
+            do_flash(&mut hm, &mut flashing, &mut flashed);
+
+            let flashing = get_flashes(&hm);
+            for f in &flashing {
+                if let Some(entry) = hm.get_mut(f) {
+                    *entry = 0;
+                }
+            }
+            flashes += flashing.len();
+        }
+
+        Ok(format!("{}", flashes))
+    }
+
+    fn part2(&self) -> anyhow::Result<String> {
+        let mut hm = self.0.clone();
+        for num in 0..1000 {
+            hm.iter_mut().for_each(|(_, x)| *x += 1);
+            let mut flashing = get_flashes(&hm);
+            let mut flashed = vec![];
+            do_flash(&mut hm, &mut flashing, &mut flashed);
+            if flashed.len() == 100 {
+                return Ok(format!("{}", num + 1));
+            }
+            let flashing = get_flashes(&hm);
+            for f in &flashing {
+                if let Some(entry) = hm.get_mut(f) {
+                    *entry = 0;
+                }
+            }
+        }
+        Err(anyhow::Error::msg("It did not flash 100 times :("))
+    }
+}
+
+fn get_flashes(hm: &FlashMap) -> Vec<(i32, i32)> {
+    hm.iter().filter(|(_, &x)| x > 9).map(|(&p, _)| p).collect::<Vec<_>>()
+}
+
+fn do_flash(mut hm: &mut FlashMap, mut flashing: &mut Vec<(i32, i32)>, mut flashed: &mut Vec<(i32, i32)>) {
+    if let Some((x, y)) = flashing.pop() {
+        flashed.push((x, y));
+        for xn in (x - 1)..=(x + 1) {
+            for yn in (y - 1)..=(y + 1) {
+                if let Some(e) = hm.get_mut(&(xn, yn)) {
+                    *e += 1;
+                    if *e > 9 {
+                        if !flashed.contains(&(xn, yn)) && !flashing.contains(&(xn, yn)) {
+                            flashing.push((xn, yn))
+                        }
+                    }
+                }
+            }
+        }
+        do_flash(&mut hm, &mut flashing, &mut flashed)
+    }
+}
+
+fn print_flashes(map: &FlashMap, x_max: i32, y_max: i32) {
+    let mut v: Vec<Vec<i32>> = Vec::new();
+    for y in 0..y_max {
+        let mut col = Vec::new();
+        for x in 0..x_max {
+            col.push(*map.get(&(x, y)).unwrap());
+        }
+        v.push(col);
+    }
+    for line in v {
+        for ch in line {
+            print!("{}", ch)
+        }
+        println!()
+    }
+    println!()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Day;
+    use crate::day11::Day11;
+
+    const INPUT: &str = r"5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526";
+
+    #[test]
+    fn part1_test() -> anyhow::Result<()> {
+        let d = Day11::init(INPUT.to_string())?;
+        assert_eq!("1656", d.part1()?);
+        Ok(())
+    }
+
+    #[test]
+    fn part2_test() -> anyhow::Result<()> {
+        let d = Day11::init(INPUT.to_string())?;
+        assert_eq!("195", d.part2()?);
+        Ok(())
+    }
+
+    #[test]
+    fn part1_real() -> anyhow::Result<()> {
+        let d = Day11::init(crate::load_input("11")?)?;
+        assert_eq!("1647", d.part1()?);
+        Ok(())
+    }
+
+    #[test]
+    fn part2_real() -> anyhow::Result<()> {
+        let d = Day11::init(crate::load_input("11")?)?;
+        assert_eq!("348", d.part2()?);
+        Ok(())
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index d60ce3c..fa76862 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,6 +13,7 @@ use anyhow::Result;
 use crate::day08::Day08;
 use crate::day09::Day09;
 use crate::day10::Day10;
+use crate::day11::Day11;
 
 mod day;
 mod day01;
@@ -25,6 +26,7 @@ mod day07;
 mod day08;
 mod day09;
 mod day10;
+mod day11;
 
 fn load_input(day: &str) -> Result<String> {
     read_to_string(format!("./input/day{}", day)).map_err(|x| x.into())
@@ -69,7 +71,8 @@ fn main() -> anyhow::Result<()> {
                                        Box::new(Day07::init(load_input("07")?)?),
                                        Box::new(Day08::init(load_input("08")?)?),
                                        Box::new(Day09::init(load_input("09")?)?),
-                                       Box::new(Day10::init(load_input("10")?)?),];
+                                       Box::new(Day10::init(load_input("10")?)?),
+                                       Box::new(Day11::init(load_input("11")?)?),];
 
     let _verbosity = matches.occurrences_of("v");
     if matches.is_present("all") {