diff --git a/src/main.rs b/src/main.rs
index a8822d0..fc096e9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,27 +1,36 @@
 struct Solution;
 mod arr;
+
 impl Solution {
-    pub fn next_greatest_letter(letters: Vec<char>, target: char) -> char {
-        let mut index = 1e5 as usize;
-        for i in 0..letters.len() {
-            if letters[i] > target {
-                if index == 1e5 as usize {
-                    index = i;
-                } else {
-                    if letters[i] < letters[index] {
-                        index = i;
-                    }
-                }
+    pub fn sp(s : &str)-> String{
+        if s.len() <= 2 {
+            return s.to_string();
+        }
+        let mut left = 0;
+        let mut cnt = 0;
+        let sb = s.as_bytes();
+        let mut arr = Vec::new();
+        for i in 0..s.len() {
+            if sb[i] == b'1' {
+                cnt += 1;
+            }else {
+                cnt -= 1;
+            }
+            if cnt == 0 {
+                arr.push(format!("1{}0",Self::sp(&s[left + 1 .. i])));
+                left = i + 1;
             }
         }
-        if index == 1e5 as usize {
-            letters[0]
-        } else {
-            letters[index]
-        }
+        arr.sort_unstable_by(|a,b| b.cmp(a));
+        arr.join("")
+    }
+    pub fn make_largest_special(s: String) -> String {
+        Self::sp(s.as_str())
     }
 }
 fn main() {
-    let result = Solution::next_greatest_letter(vec!['c', 'f', 'j'], 'a');
+    let result = Solution::make_largest_special(
+         "101101101010101010001010101010110011011010001100".to_string(),
+    );
     println!("{:?}", result);
-}
+}
\ No newline at end of file