diff --git a/src/main.rs b/src/main.rs
index 972a2b6..d05e0d0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,36 +6,25 @@ mod tree;
 
 struct Solution {}
 impl Solution {
-    pub fn decode_string(s: String) -> String {
-        let mut st = vec![];
-        let mut local = "".to_string();
-        let mut cnt = 0;
-        // let mut layer = 0;
-        for c in s.chars() {
-            if c.is_ascii_digit() {
-                cnt = cnt * 10 + c.to_digit(10).unwrap() as usize;
-                continue;
+    pub fn maximum_length_substring(s: String) -> i32 {
+        let s = s.bytes().map(|x| x as usize).collect::<Vec<_>>();
+        let mut arr = vec![0; 'z' as usize + 1];
+        let mut l = 0;
+        let mut ans = 0;
+        for r in 0..s.len() {
+            arr[s[r]] += 1;
+            while arr[s[r]] > 2 {
+                arr[s[l]] -= 1;
+                l += 1;
             }
-            if c == '[' {
-                st.push((local,cnt));
-                cnt = 0;
-                local = "".to_string();
-                continue;
-            }
-            if c == ']' {
-                let (mut str, cnt) = st.pop().unwrap();
-                str += &local.repeat( cnt);
-                local = str;
-                continue;
-            }
-            local.push(c);
+            ans = ans.max(r - l + 1);
         }
-        local
+        ans as i32
     }
 }
 fn main() {
     println!(
         "{:?}",
-        Solution::decode_string("3[a2[c]]".to_string())
+        Solution::maximum_length_substring("bcbbbcba".to_string())
     );
 }