valid parentheses solution

Author: jylee2033

valid-parentheses/jylee2033.py

@@ -0,0 +1,25 @@
+class Solution:
+    def isValid(self, s: str) -> bool:
+        close_to_open = {')': '(', '}': '{', ']': '['}
+        stack = [] # Open brackets
+
+        if len(s) % 2 == 1:
+            return False
+
+        for ch in s:
+            # Open bracket
+            if ch in close_to_open.values():
+                stack.append(ch)
+            # Close bracket
+            else:
+                if len(stack) == 0:
+                    return False
+
+                expected = close_to_open[ch]
+                if stack.pop() != expected:
+                    return False
+
+        return len(stack) == 0
+
+# Time Complexity: O(n)
+# Space Complexity: O(n)