合法的括号

lc20. Valid Parentheses.py

@@ -0,0 +1,17 @@
+class Solution:
+    def isValid(self, s):
+        """
+        :type s: str
+        :rtype: bool
+        """
+        d = {'(': ')', '[': ']', '{': '}'}
+        stack = []
+        for c in s:
+            if c in d:
+                stack.append(c)
+            else:
+                if len(stack) == 0:
+                    return False
+                elif d[stack.pop()] != c:
+                    return False
+        return len(stack) == 0