diff --git a/.aoc_tiles/tiles/2024/24.png b/.aoc_tiles/tiles/2024/24.png
index 89f755a..b966019 100644
Binary files a/.aoc_tiles/tiles/2024/24.png and b/.aoc_tiles/tiles/2024/24.png differ
diff --git a/.aoc_tiles/tiles/2024/25.png b/.aoc_tiles/tiles/2024/25.png
index e1ab8d3..a1daeb8 100644
Binary files a/.aoc_tiles/tiles/2024/25.png and b/.aoc_tiles/tiles/2024/25.png differ
diff --git a/README.md b/README.md
index bd4c125..dfc7c92 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 <!-- AOC TILES BEGIN -->
 <h1 align="center">
-  2024 - 46 ⭐ - Rust
+  2024 - 48 ⭐ - Rust
 </h1>
 <a href="src/day1.rs">
   <img src=".aoc_tiles/tiles/2024/01.png" width="161px">
@@ -74,4 +74,7 @@
 <a href="src/day24.rs">
   <img src=".aoc_tiles/tiles/2024/24.png" width="161px">
 </a>
+<a href="src/day25.rs">
+  <img src=".aoc_tiles/tiles/2024/25.png" width="161px">
+</a>
 <!-- AOC TILES END -->
diff --git a/src/day25.rs b/src/day25.rs
new file mode 100644
index 0000000..2b8d7b4
--- /dev/null
+++ b/src/day25.rs
@@ -0,0 +1,143 @@
+use aoc_runner_derive::aoc;
+use itertools::Itertools;
+
+enum LockKey {
+    Lock,
+    Key,
+}
+
+#[derive(Clone, Debug)]
+struct LockPile {
+    keys: Vec<Vec<usize>>,
+    locks: Vec<Vec<usize>>,
+}
+
+fn parse_grid(lines: &Vec<&str>) -> (LockKey, Vec<usize>) {
+    assert_eq!(lines.len(), 7);
+    if lines[0].chars().all(|c| c == '#') {
+        // lock
+        let mut pins = vec![0; 5];
+        for row in 1..lines.len() {
+            let row_s = lines[row];
+            for i in 0..row_s.len() {
+                if row_s.chars().nth(i) == Some('#') {
+                    pins[i] = row
+                }
+            }
+        }
+        (LockKey::Lock, pins)
+    } else if lines[6].chars().all(|c| c == '#') {
+        // key
+        let mut pins = vec![5; 5];
+        for row in (1..lines.len()).rev() {
+            let row_s = lines[row];
+            for i in 0..row_s.len() {
+                if row_s.chars().nth(i) == Some('#') {
+                    pins[i] = 6 - row
+                }
+            }
+        }
+        (LockKey::Key, pins)
+    } else {
+        panic!("not a lock or a key: {:?}", lines);
+    }
+}
+
+fn parse(input: &str) -> LockPile {
+    let mut locks = Vec::new();
+    let mut keys = Vec::new();
+    let mut accum: Vec<&str> = Vec::new();
+    for line in input.lines() {
+        if line == "" {
+            let (lk, pins) = parse_grid(&accum);
+            match lk {
+                LockKey::Lock => locks.push(pins),
+                LockKey::Key => keys.push(pins),
+            }
+            accum.clear();
+        } else {
+            accum.push(line);
+        }
+    }
+    if accum.len() != 0 {
+        let (lk, pins) = parse_grid(&accum);
+        match lk {
+            LockKey::Lock => locks.push(pins),
+            LockKey::Key => keys.push(pins),
+        }
+    }
+    LockPile { keys, locks }
+}
+
+fn test_lock_key(lock: &Vec<usize>, key: &Vec<usize>) -> bool {
+    !lock.iter().zip(key.iter()).any(|(lp, kp)| lp + kp > 5)
+}
+
+#[aoc(day25, part1)]
+pub fn part1(input: &str) -> i64 {
+    let lockpile = parse(input);
+
+    lockpile
+        .locks
+        .iter()
+        .cartesian_product(lockpile.keys.iter())
+        .filter(|(l, k)| test_lock_key(l, k))
+        .count() as i64
+}
+
+#[aoc(day25, part2)]
+pub fn part2(_input: &str) -> String {
+    "run the other solutions for day 25 part 2!".to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    const EXAMPLE: &str = "#####
+.####
+.####
+.####
+.#.#.
+.#...
+.....
+
+#####
+##.##
+.#.##
+...##
+...#.
+...#.
+.....
+
+.....
+#....
+#....
+#...#
+#.#.#
+#.###
+#####
+
+.....
+.....
+#.#..
+###..
+###.#
+###.#
+#####
+
+.....
+.....
+.....
+#....
+#.#..
+#.#.#
+#####";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(EXAMPLE), 3);
+    }
+
+    #[test]
+    fn part2_example() {}
+}
diff --git a/src/lib.rs b/src/lib.rs
index 6cfecaf..ee2182e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -15,6 +15,7 @@ pub mod day21;
 pub mod day22;
 pub mod day23;
 pub mod day24;
+pub mod day25;
 pub mod day3;
 pub mod day4;
 pub mod day5;