leetcode: finished #921

content/leetcode/2023/9.md

@@ -3,6 +3,34 @@ title: 2023.9
 draft: false
 ---
 
+# 2023.9.13
+
+```python
+#
+# @lc app=leetcode.cn id=921 lang=python3
+#
+# [921] 使括号有效的最少添加
+#
+
+
+# @lc code=start
+class Solution:
+    def minAddToMakeValid(self, s: str) -> int:
+        stack = []
+        for i in s:
+            if i == "(":
+                stack.append(i)
+            else:
+                if stack and stack[-1] == "(":
+                    stack.pop()
+                else:
+                    stack.append(i)
+        return len(stack)
+
+
+# @lc code=end
+```
+
 # 2023.9.12
 
 ```python