394. 字符串解码

src/main.rs

@@ -6,23 +6,36 @@ mod tree;
 
 struct Solution {}
 impl Solution {
-    pub fn training_plan(head: Option<Box<ListNode>>, cnt: i32) -> Option<Box<ListNode>> {
-        let mut fast = &head;
-
-        for i in 0..cnt {
-            fast = &fast.as_ref()?.next;
+    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;
+            }
+            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);
         }
-        let mut slow = &head;
-        while fast.is_some() {
-            slow = &slow.as_ref()?.next;
-            fast = &fast.as_ref()?.next;
-        }
-        slow.clone()
+        local
     }
 }
 fn main() {
     println!(
         "{:?}",
-        Solution::training_plan(make_list(vec![2, 4, 7, 8]), 2)
+        Solution::decode_string("3[a2[c]]".to_string())
     );
 }