update 20

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