diff --git a/data/examples/12.txt b/data/examples/12.txt
new file mode 100644
index 0000000..85b768f
--- /dev/null
+++ b/data/examples/12.txt
@@ -0,0 +1,10 @@
+RRRRIICCFF
+RRRRIICCCF
+VVRRRCCFFF
+VVRCCCJFFF
+VVVVCJJCFE
+VVIVCCJJEE
+VVIIICJJEE
+MIIIIIJJEE
+MIIISIJEEE
+MMMISSJEEE
diff --git a/src/bin/12.rs b/src/bin/12.rs
new file mode 100644
index 0000000..eb20d99
--- /dev/null
+++ b/src/bin/12.rs
@@ -0,0 +1,317 @@
+advent_of_code::solution!(12);
+
+use itertools::Itertools;
+use std::collections::HashMap;
+use std::iter::successors;
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+struct Pos {
+    x: isize,
+    y: isize,
+}
+
+impl Pos {
+    fn origin() -> Self {
+        Self { x: 0, y: 0 }
+    }
+
+    fn diff(&self, other: &Self) -> Self {
+        Self {
+            x: self.x - other.x,
+            y: self.y - other.y,
+        }
+    }
+
+    fn init(x: usize, y: usize) -> Self {
+        Self {
+            x: x as isize,
+            y: y as isize,
+        }
+    }
+
+    fn neighbors(&self) -> Vec<Pos> {
+        vec![
+            Pos {
+                x: self.x - 1,
+                y: self.y,
+            },
+            Pos {
+                x: self.x,
+                y: self.y - 1,
+            },
+            Pos {
+                x: self.x + 1,
+                y: self.y,
+            },
+            Pos {
+                x: self.x,
+                y: self.y + 1,
+            },
+        ]
+    }
+
+    fn add(&self, other: &Self) -> Self {
+        Self {
+            x: self.x + other.x,
+            y: self.y + other.y,
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Region {
+    c: char,
+    ps: Vec<Pos>,
+}
+
+impl Region {
+    fn init(c: char, p: Pos) -> Self {
+        Self { c, ps: vec![p] }
+    }
+
+    fn fill(&mut self, remains: &mut Vec<(char, Pos)>) {
+        if remains.is_empty() {
+            return;
+        }
+        let mut found: bool = false;
+        for i in 0..remains.len() {
+            if remains[i].0 == self.c
+                && remains[i].1.neighbors().iter().any(|p| self.ps.contains(p))
+            {
+                let (_, p) = remains.remove(i);
+                self.ps.push(p);
+                found = true;
+                break;
+            }
+        }
+        if found {
+            self.fill(remains);
+        }
+    }
+
+    fn area(&self) -> usize {
+        let area = self.ps.len();
+        // println!("Region {:?} -> area: {:?}", self.c, area);
+        area
+    }
+
+    fn perimeter(&self) -> usize {
+        self.ps
+            .clone()
+            .into_iter()
+            .flat_map(|p| p.neighbors())
+            .filter(|p| !self.ps.contains(p))
+            .collect::<Vec<_>>()
+            .len()
+    }
+
+    fn sides(&self) -> usize {
+        // Count sides or count angles...
+
+        // Outward:
+
+        // .X
+        // XAA <- 2 neighbors are missing from region -> 1 angle
+        // .AA
+        // XAX <- 3 neighbors are missing from region -> 2 angles
+        // .X.
+
+        // .A.
+        // XAX <- 2 neighbors are missing BUT coords cancel out -> 0 angles
+        // .A.
+
+        // .X.
+        // XAX <- 4 neighbors missing -> 4 angles ...
+        // .X.
+
+        // Inward:
+
+        // .XA <- same foreign neighbor for 2 pieces -> 1 angle
+        // AAA
+
+        // AXA <- same foreign neighbor for 3 pieces -> 2 angles
+        // AAA
+
+        // AAA
+        // AXA <- same foreign neighbor for 4 pieces -> 4 angles
+        // AAA
+
+        // println!("Region {}", self.c);
+
+        let data: Vec<(Pos, Vec<Pos>)> = self
+            .ps
+            .clone()
+            .into_iter()
+            .map(|p| {
+                (
+                    p.clone(),
+                    p.neighbors()
+                        .into_iter()
+                        .filter(|pn| !self.ps.contains(pn))
+                        .collect::<Vec<_>>(),
+                )
+            })
+            .collect();
+
+        let mut neighbors_map: HashMap<Pos, Vec<Pos>> = HashMap::new();
+        let mut outward_angles = 0;
+        data.iter().for_each(|(p, ps)| {
+            let l = match ps.len() {
+                2 => {
+                    match ps
+                        .into_iter()
+                        .fold(Pos::origin(), |acc, p2| acc.add(&p.diff(p2)))
+                    {
+                        Pos { x: 0, y: 0 } => 0,
+                        _ => 1,
+                    }
+                }
+                3 => 2,
+                4 => 4,
+                _ => 0,
+            };
+            let neighbors_vec = ps
+                .into_iter()
+                .fold(Pos::origin(), |acc, p2| acc.add(&p.diff(p2)));
+            // println!("  * Outward angle(s) around: {:?} -> {}", p, l);
+            // println!("     Neighbors vec: {:?}", neighbors_vec);
+            outward_angles += l;
+            for pn in ps {
+                neighbors_map.entry(pn.clone()).or_default().push(p.clone());
+            }
+        });
+        // println!("  Outward Angles: {}", outward_angles);
+        let inward_angles = neighbors_map
+            .values()
+            .map(|ps| {
+                let l = match ps.len() {
+                    2 => 1,
+                    3 => 2,
+                    4 => 4,
+                    _ => 0,
+                };
+                // println!("  * Inward angle(s) around: ?? -> {}", l);
+                l
+            })
+            .sum::<usize>();
+        // println!("Region {:} -> inward angles: {}, outward angles: {}", self.c, inward_angles, outward_angles);
+        // println!("   -> sides: {}", inward_angles + outward_angles);
+        inward_angles + outward_angles
+    }
+}
+
+fn count_sides(path: &mut Vec<Pos>) -> usize {
+    if path.len() <= 1 {
+        return 0;
+    }
+
+    let start = path.remove(0);
+    let directions = [
+        Pos { x: 0, y: 1 },  // up
+        Pos { x: 1, y: 0 },  // right
+        Pos { x: 0, y: -1 }, // down
+        Pos { x: -1, y: 0 }, // left
+    ];
+    let steps = successors(Some((start, 1, None)), |(cur, sides, d_idx)| {
+        // println!("Current: {:?}", cur);
+        if path.is_empty() {
+            return None;
+        }
+        for i in 0..4 {
+            let dir = directions[(d_idx.unwrap_or(0) + i) % 4].clone();
+            let next = cur.add(&dir);
+            if let Some(ofs) = path.iter().position(|p| p == &next) {
+                // println!("  Trying direction {:?} -> {:?} (Found!)", dir, next);
+                let new_cur = path.remove(ofs);
+                let new_sides = sides
+                    + if d_idx.is_some() && i > 0 {
+                        // println!("(new direction, incrementing sides: {:?})", sides + 1);
+                        1
+                    } else {
+                        // println!("(same direction, sides: {:?})", sides);
+                        0
+                    };
+                return Some((new_cur, new_sides, Some(d_idx.unwrap_or(0) + i)));
+                // } else {
+                // println!("  Trying direction {:?} -> {:?} (Not found)", dir, next);
+            }
+        }
+        let new_cur = path.remove(0);
+        // println!("No consecutive neighbor found -> Trying new side (sides: {})", sides + 1);
+        Some((new_cur, sides + 1, None))
+    })
+    .collect::<Vec<_>>();
+    steps.last().unwrap().1
+}
+
+fn parse_input(input: &str) -> Vec<Region> {
+    let mut res: Vec<Region> = Vec::new();
+    let mut pcs = input
+        .strip_suffix("\n")
+        .unwrap_or(input)
+        .lines()
+        .enumerate()
+        .flat_map(|(y, line)| {
+            line.chars()
+                .enumerate()
+                .map(|(x, c)| (c, Pos::init(x, y)))
+                .collect::<Vec<_>>()
+        })
+        .collect::<Vec<_>>();
+    // pcs.sort();
+    while !pcs.is_empty() {
+        let (c, p) = pcs.remove(0);
+        let mut r: Region = Region::init(c, p);
+        r.fill(&mut pcs); // Should filter only by relevant letters
+        res.push(r);
+    }
+    res
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    parse_input(input)
+        .iter()
+        .map(|r| r.area() * r.perimeter())
+        .sum::<usize>()
+        .into()
+}
+
+pub fn part_two(input: &str) -> Option<usize> {
+    // println!("{}", input);
+    parse_input(input)
+        .iter()
+        .map(|r| r.area() * r.sides())
+        .sum::<usize>()
+        .into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(1930));
+        // assert_eq!(result, Some(140));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(1206));
+        // assert_eq!(result, Some(80));
+    }
+}
+
+// A region of R plants with price 12 * 10 = 120.    => KO 12 * 11
+// A region of I plants with price 4 * 4 = 16.       => OK
+// A region of C plants with price 14 * 22 = 308.    => OK
+// A region of F plants with price 10 * 12 = 120.    => KO 10 * 13
+// A region of V plants with price 13 * 10 = 130.    => KO 13 * 11
+// A region of J plants with price 11 * 12 = 132.    => OK
+// A region of C plants with price 1 * 4 = 4.        => OK
+// A region of E plants with price 13 * 8 = 104.     => KO 13 * 9
+// A region of I plants with price 14 * 16 = 224.    => OK
+// A region of M plants with price 5 * 6 = 30.       => KO 5 * 7
+// A region of S plants with price 3 * 6 = 18.       => OK