diff --git a/Cargo.toml b/Cargo.toml
index 7deb2fb..6d5b77c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,6 +16,7 @@ full = [
     "day9",
     "day10",
     "day11",
+    "day12",
 ]
 default = ["full"]
 day1 = []
@@ -29,6 +30,7 @@ day8 = []
 day9 = []
 day10 = []
 day11 = []
+day12 = []
 
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
diff --git a/inputs/day12/example.txt b/inputs/day12/example.txt
new file mode 100644
index 0000000..0b328f1
--- /dev/null
+++ b/inputs/day12/example.txt
@@ -0,0 +1,10 @@
+RRRRIICCFF
+RRRRIICCCF
+VVRRRCCFFF
+VVRCCCJFFF
+VVVVCJJCFE
+VVIVCCJJEE
+VVIIICJJEE
+MIIIIIJJEE
+MIIISIJEEE
+MMMISSJEEE
\ No newline at end of file
diff --git a/inputs/day12/example_2.txt b/inputs/day12/example_2.txt
new file mode 100644
index 0000000..cc213c5
--- /dev/null
+++ b/inputs/day12/example_2.txt
@@ -0,0 +1,5 @@
+OOOOO
+OXOXO
+OOOOO
+OXOXO
+OOOOO
\ No newline at end of file
diff --git a/src/day12.rs b/src/day12.rs
new file mode 100644
index 0000000..e9cf98d
--- /dev/null
+++ b/src/day12.rs
@@ -0,0 +1,188 @@
+#![allow(
+    clippy::cast_sign_loss,
+    clippy::cast_possible_wrap,
+    clippy::too_many_lines
+)]
+use std::collections::HashSet;
+
+use tracing::debug;
+
+pub fn pt1(input: &str) -> usize {
+    let mut res = 0;
+    let mut visited: HashSet<(usize, usize)> = HashSet::new();
+    let fields = input
+        .lines()
+        .enumerate()
+        .flat_map(|(y, line)| line.chars().enumerate().map(move |(x, c)| (c, x, y)))
+        .collect::<Vec<_>>();
+    for &(c, x, y) in &fields {
+        if visited.contains(&(x, y)) {
+            continue;
+        }
+        let mut current_matching: HashSet<(usize, usize)> = HashSet::new();
+        current_matching.insert((x, y));
+        visited.insert((x, y));
+        let mut previous_matching = 0;
+        let mut cur_matching = current_matching.len();
+        while previous_matching != cur_matching {
+            let m = current_matching.clone();
+            let v = visited.clone();
+            for &(_cc, cx, cy) in fields
+                .iter()
+                .filter(|(cc, _, _)| *cc == c)
+                .filter(|(_cc, cx, cy)| !v.contains(&(*cx, *cy)))
+                .filter(|&&(_cc, cx, cy)| {
+                    m.iter().any(|&(mx, my)| {
+                        (mx.abs_diff(cx) == 1 && my == cy) || (mx == cx && my.abs_diff(cy) == 1)
+                    })
+                })
+            {
+                current_matching.insert((cx, cy));
+                visited.insert((cx, cy));
+            }
+            previous_matching = cur_matching;
+            cur_matching = current_matching.len();
+        }
+        debug!("char: {c} -> current_matching = {current_matching:?}");
+        let area = current_matching.len();
+        let perimeter = get_perim(&current_matching);
+        debug!("area: {area}, perimeter:{perimeter}");
+        res += area * perimeter;
+    }
+    res
+}
+fn get_perim(current_matching: &HashSet<(usize, usize)>) -> usize {
+    let mut perim = 0;
+    for &(x, y) in current_matching {
+        if x == 0 || !current_matching.contains(&(x - 1, y)) {
+            perim += 1;
+        }
+        if y == 0 || !current_matching.contains(&(x, y - 1)) {
+            perim += 1;
+        }
+        if !current_matching.contains(&(x + 1, y)) {
+            perim += 1;
+        }
+        if !current_matching.contains(&(x, y + 1)) {
+            perim += 1;
+        }
+    }
+    perim
+}
+
+fn get_perimv2(current_matching: &HashSet<(usize, usize)>) -> usize {
+    let mut perim = 0;
+    for &(x, y) in current_matching {
+        let left_is_empty = x == 0 || !current_matching.contains(&(x - 1, y));
+        let top_is_empty = y == 0 || !current_matching.contains(&(x, y - 1));
+        let right_is_empty = !current_matching.contains(&(x + 1, y));
+        let bottom_is_empty = !current_matching.contains(&(x, y + 1));
+        let top_left_is_empty = x == 0 || y == 0 || !current_matching.contains(&(x - 1, y - 1));
+        let top_right_is_empty = y == 0 || !current_matching.contains(&(x + 1, y - 1));
+        let bottom_left_is_empty = x == 0 || !current_matching.contains(&(x - 1, y + 1));
+        let bottom_right_is_empty = !current_matching.contains(&(x + 1, y + 1));
+        if left_is_empty && top_is_empty {
+            perim += 1;
+        }
+        if left_is_empty && bottom_is_empty {
+            perim += 1;
+        }
+        if right_is_empty && top_is_empty {
+            perim += 1;
+        }
+        if right_is_empty && bottom_is_empty {
+            perim += 1;
+        }
+        if !top_is_empty && top_left_is_empty && !left_is_empty {
+            perim += 1;
+        }
+        if !bottom_is_empty && bottom_left_is_empty && !left_is_empty {
+            perim += 1;
+        }
+        if top_right_is_empty && !top_is_empty && !right_is_empty {
+            perim += 1;
+        }
+        if bottom_right_is_empty && !bottom_is_empty && !right_is_empty {
+            perim += 1;
+        }
+    }
+    perim
+}
+
+pub fn pt2(input: &str) -> usize {
+    let mut res = 0;
+    let mut visited: HashSet<(usize, usize)> = HashSet::new();
+    let fields = input
+        .lines()
+        .enumerate()
+        .flat_map(|(y, line)| line.chars().enumerate().map(move |(x, c)| (c, x, y)))
+        .collect::<Vec<_>>();
+    for &(c, x, y) in &fields {
+        if visited.contains(&(x, y)) {
+            continue;
+        }
+        let mut current_matching: HashSet<(usize, usize)> = HashSet::new();
+        current_matching.insert((x, y));
+        visited.insert((x, y));
+        let mut previous_matching = 0;
+        let mut cur_matching = current_matching.len();
+        while previous_matching != cur_matching {
+            let m = current_matching.clone();
+            let v = visited.clone();
+            for &(_cc, cx, cy) in fields
+                .iter()
+                .filter(|(cc, _, _)| *cc == c)
+                .filter(|(_cc, cx, cy)| !v.contains(&(*cx, *cy)))
+                .filter(|&&(_cc, cx, cy)| {
+                    m.iter().any(|&(mx, my)| {
+                        (mx.abs_diff(cx) == 1 && my == cy) || (mx == cx && my.abs_diff(cy) == 1)
+                    })
+                })
+            {
+                current_matching.insert((cx, cy));
+                visited.insert((cx, cy));
+            }
+            previous_matching = cur_matching;
+            cur_matching = current_matching.len();
+        }
+        debug!("char: {c} -> current_matching = {current_matching:?}");
+        let area = current_matching.len();
+        let perimeter = get_perimv2(&current_matching);
+        debug!("area: {area}, perimeter:{perimeter}");
+        res += area * perimeter;
+    }
+    res
+}
+
+#[cfg(test)]
+mod tests {
+    use tracing_test::traced_test;
+
+    use super::{pt1, pt2};
+    use std::fs::read_to_string;
+
+    #[traced_test]
+    #[test]
+    pub fn test_pt1() {
+        let input =
+            read_to_string("./inputs/day12/example.txt").expect("Missing example.txt for day12");
+        assert_eq!(pt1(&input), 1930)
+    }
+
+    #[traced_test]
+    #[test]
+    pub fn test_pt1_2() {
+        let input = read_to_string("./inputs/day12/example_2.txt")
+            .expect("Missing example_2.txt for day12");
+        assert_eq!(pt1(&input), 772)
+    }
+
+    #[traced_test]
+    #[test]
+    pub fn test_pt2() {
+        let input =
+            read_to_string("./inputs/day12/example.txt").expect("Missing example.txt for day12");
+
+        assert_eq!(pt2(&input), 1206)
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index e373132..04036e9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -25,6 +25,8 @@ mod day09;
 mod day10;
 #[cfg(feature = "day11")]
 mod day11;
+#[cfg(feature = "day12")]
+mod day12;
 
 fn main() -> eyre::Result<()> {
     color_eyre::install()?;
@@ -53,6 +55,8 @@ fn main() -> eyre::Result<()> {
     solve_day(10, day10::pt1, day10::pt2);
     #[cfg(feature = "day11")]
     solve_day(11, day11::pt1, day11::pt2);
+    #[cfg(feature = "day12")]
+    solve_day(12, day12::pt1, day12::pt2);
     Ok(())
 }