diff --git a/2015/11/src/main.rs b/2015/11/src/main.rs
index 65c822f..485e122 100644
--- a/2015/11/src/main.rs
+++ b/2015/11/src/main.rs
@@ -1,16 +1,24 @@
+use std::collections::HashSet;
+
+
 fn main() {
-    println!("Hello, world!");
+    let first = generate("hxbxwxba");
+    println!("{}", first);
+    println!("{}", generate(&first));
 }
 
 fn validate(input: &str) -> bool {
-    let count = input.chars()
+    let count = input
+        .chars()
         .collect::<Vec<char>>()
         .windows(3)
         .filter(|x| x[0] >= 'a' && x[2] <= 'z')
-        .filter(|x| (x[1] as i8 - x[0] as i8) == 1 && (x[2] as i8 - x[1] as i8) == 1)
+        .filter(|x| {
+            (x[1] as i8 - x[0] as i8) == 1 && (x[2] as i8 - x[1] as i8) == 1
+        })
         .count();
 
-    if count <= 0 {
+    if count == 0 {
         return false;
     }
 
@@ -20,13 +28,13 @@ fn validate(input: &str) -> bool {
         }
     }
 
-    let count = input.chars()
-        .collect::<Vec<char>>()
+    let count = input.as_bytes()
         .windows(2)
         .filter(|x| x[0] == x[1])
-        .count();
+        .map(|x| x[0])
+        .collect::<HashSet<_>>();
 
-    if count < 2 {
+    if count.len() < 2 {
         return false;
     }
 
@@ -34,15 +42,31 @@ fn validate(input: &str) -> bool {
 }
 
 fn generate(input: &str) -> String {
-    let mut password = String::from(input);
+    let mut password = input.as_bytes().to_vec();
 
-    password
+    loop {
+        for i in (0..8).rev() {
+            password[i] += 1;
+
+            if password[i] > b'z' {
+                password[i] = b'a';
+            } else {
+                break;
+            }
+        }
+
+        if validate(&String::from_utf8_lossy(&password)) {
+            break;
+        }
+    }
+
+    String::from_utf8_lossy(&password).into()
 }
 
 
 #[cfg(test)]
 mod tests {
-    use super::{validate, generate};
+    use super::{generate, validate};
 
     #[test]
     fn test_validate() {