From 579e90ba9491d44c675a8462e59388d59e0449a7 Mon Sep 17 00:00:00 2001
From: sangge-rockpi <2251250136@qq.com>
Date: Sat, 20 Jan 2024 18:19:37 +0800
Subject: [PATCH] update 20

---
 leetcode/20.py | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/leetcode/20.py b/leetcode/20.py
index e3c5727..cfca09e 100644
--- a/leetcode/20.py
+++ b/leetcode/20.py
@@ -4,6 +4,8 @@
 
 class Solution:
     def isValid(self, s: str) -> bool:
+        """
+        # too slow
         symbol_dict = {"(": ")", "{": "}", "[": "]"}
         stack = []
         for i in s:
@@ -16,8 +18,8 @@ class Solution:
             try:
                 if symbol_dict[stack_top] == i:
                     continue
-                else:
-                    stack.append(stack_top)
+
+                 stack.append(stack_top)
 
             except KeyError:
                 return False
@@ -28,3 +30,20 @@ class Solution:
             return False
 
         return True
+        """
+
+        # Optimized solution
+        bracket_map = {")": "(", "}": "{", "]": "["}
+        stack = []
+
+        for char in s:
+            if char in bracket_map:
+                top_element = stack.pop() if stack else "#"
+
+                if bracket_map[char] != top_element:
+                    return False
+
+            else:
+                stack.append(char)
+
+        return not stack