From 7978a94372066596bf73cb447f8c6a081df087ce Mon Sep 17 00:00:00 2001
From: Joseph Chamochumbi <sephxd1234@gmail.com>
Date: Sat, 11 Dec 2021 09:21:42 +0100
Subject: [PATCH] feat: Day 11 2021 :star: :star2: Rust solution

---
 2021/day-11/Cargo.toml  |   9 ++
 2021/day-11/src/main.rs | 203 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 212 insertions(+)
 create mode 100644 2021/day-11/Cargo.toml
 create mode 100644 2021/day-11/src/main.rs

diff --git a/2021/day-11/Cargo.toml b/2021/day-11/Cargo.toml
new file mode 100644
index 0000000..cd805e9
--- /dev/null
+++ b/2021/day-11/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+authors = ["Joseph Chamochumbi <sephxd1234@gmail.com>"]
+edition = "2018"
+name = "day-11"
+version = "0.1.0"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[dependencies]
+aoc = {git = "https://github.com/icyJoseph/advent-of-code.git"}
diff --git a/2021/day-11/src/main.rs b/2021/day-11/src/main.rs
new file mode 100644
index 0000000..93b5ac6
--- /dev/null
+++ b/2021/day-11/src/main.rs
@@ -0,0 +1,203 @@
+use aoc;
+
+use std::cell::Cell;
+use std::collections::{HashSet, VecDeque};
+use std::hash::{Hash, Hasher};
+
+#[derive(PartialEq, Eq)]
+struct Octopus {
+    value: Cell<u32>,
+    index: usize,
+}
+
+impl Hash for Octopus {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.index.hash(state);
+    }
+}
+
+impl Octopus {
+    fn new(c: char, index: usize) -> Self {
+        let value = c.to_digit(10).expect("Failed to parse cell value");
+        Octopus {
+            value: Cell::new(value),
+            index,
+        }
+    }
+
+    fn get_value(&self) -> u32 {
+        self.value.get()
+    }
+
+    fn radiate(&self) {
+        self.value.set(self.value.get() + 1);
+    }
+
+    fn reset(&self) {
+        self.value.set(0);
+    }
+}
+
+fn solve(raw: String) -> () {
+    let rows = raw.trim().split("\n").collect::<Vec<&str>>();
+
+    let height = rows[0].len();
+    let width = rows[0].chars().count();
+
+    let grid = rows
+        .iter()
+        .enumerate()
+        .flat_map(|(y, row)| {
+            row.chars()
+                .enumerate()
+                .map(|(x, c)| Octopus::new(c, norm(x, y, width)))
+                .collect::<Vec<Octopus>>()
+        })
+        .collect::<Vec<Octopus>>();
+
+    let adj = calc_adj(height, width);
+
+    let mut step = 0;
+    let mut total_flashes = 0;
+
+    loop {
+        if grid.iter().all(|oct| oct.get_value() == 0) {
+            break;
+        }
+
+        step += 1;
+
+        grid.iter().for_each(|oct| oct.radiate());
+
+        let mut scheduled: VecDeque<&Octopus> =
+            grid.iter().filter(|oct| oct.get_value() > 9).collect::<_>();
+
+        let mut radiated: HashSet<&Octopus> = HashSet::new();
+
+        loop {
+            let next = scheduled.pop_front();
+
+            match next {
+                None => break,
+
+                Some(current_oct) => {
+                    let index = current_oct.index;
+
+                    if radiated.contains(current_oct) {
+                        continue;
+                    }
+
+                    radiated.insert(current_oct);
+
+                    for v in &adj[index] {
+                        let v_oct = &grid[*v];
+
+                        v_oct.radiate();
+
+                        if v_oct.get_value() > 9 {
+                            if !radiated.contains(v_oct) {
+                                scheduled.push_back(v_oct)
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        total_flashes += radiated.len();
+
+        for oct in radiated {
+            oct.reset();
+        }
+
+        if step == 100 {
+            println!("Part One: {}", total_flashes);
+        }
+    }
+
+    println!("Part Two: {}", step);
+}
+
+fn main() {
+    let input = aoc::get_input(2021, 11);
+
+    solve(input);
+}
+
+// Utilities
+#[allow(dead_code)]
+fn normal(x: usize, y: usize, width: usize) -> usize {
+    x + y * width
+}
+
+#[allow(dead_code)]
+fn rev_normal(norm: usize, width: usize) -> (usize, usize) {
+    (norm % width, norm / width)
+}
+
+#[allow(dead_code)]
+fn parse_num<T: std::str::FromStr>(str: &str) -> T {
+    match str.trim().parse::<T>() {
+        Ok(n) => n,
+        _ => panic!("Error parsing"),
+    }
+}
+#[allow(dead_code)]
+fn to_int(bin: &str) -> u32 {
+    match u32::from_str_radix(bin, 2) {
+        Ok(n) => n,
+        _ => panic!("Error parsing binary to integer"),
+    }
+}
+
+#[allow(dead_code)]
+fn string_vec<T: std::string::ToString>(vec: &Vec<T>, separator: &str) -> String {
+    vec.iter()
+        .map(|x| x.to_string())
+        .collect::<Vec<String>>()
+        .join(separator)
+}
+
+type Adj = Vec<Vec<usize>>;
+
+fn norm(x: usize, y: usize, width: usize) -> usize {
+    x + y * width
+}
+
+fn calc_adj(height: usize, width: usize) -> Adj {
+    let mut adj = vec![vec![]; height * width];
+
+    for y in 0..height {
+        for x in 0..width {
+            let index = norm(x, y, width);
+
+            if x > 0 {
+                adj[index].push(norm(x - 1, y, width));
+            }
+            if y + 1 < height {
+                adj[index].push(norm(x, y + 1, width));
+            }
+            if x + 1 < width {
+                adj[index].push(norm(x + 1, y, width));
+            }
+            if y > 0 {
+                adj[index].push(norm(x, y - 1, width));
+            }
+
+            if x > 0 && y > 0 {
+                adj[index].push(norm(x - 1, y - 1, width));
+            }
+            if x > 0 && y + 1 < height {
+                adj[index].push(norm(x - 1, y + 1, width));
+            }
+            if x + 1 < width && y > 0 {
+                adj[index].push(norm(x + 1, y - 1, width));
+            }
+            if x + 1 < width && y + 1 < height {
+                adj[index].push(norm(x + 1, y + 1, width));
+            }
+        }
+    }
+
+    adj
+}