diff --git a/2015/src/bin/day10.rs b/2015/src/bin/day10.rs
new file mode 100644
index 0000000..82ff77e
--- /dev/null
+++ b/2015/src/bin/day10.rs
@@ -0,0 +1,36 @@
+use aoc::input;
+
+fn main() {
+    let mut v = input::read_chars();
+
+    // Part 1
+    for _ in 0..40 {
+        v = step(&v);
+    }
+    println!("Length after 40 steps: {}", v.len());
+
+    // Part 2
+    for _ in 0..10 {
+        v = step(&v);
+    }
+    println!("Length after 50 steps: {}", v.len());
+}
+
+fn step(s: &str) -> String {
+    let mut count = 1;
+    let mut pc = ' ';
+    let mut result = String::new();
+    for c in s.chars() {
+        if c == pc {
+            count += 1;
+        } else if pc != ' ' {
+            result.push_str(&count.to_string());
+            result.push(pc);
+            count = 1;
+        }
+        pc = c;
+    }
+    result.push_str(&count.to_string());
+    result.push(pc);
+    result
+}