Commit 13d551e

@@ -0,0 +1,37 @@
+Image you are buliding a compiler.
+Before running any code, the compiler must check
+that the parentheses in the program are balanced.
+
+Every opening bracket must have a corresponding closing bracket.
+We can approximate this using strings.
+
+Given a string containing just the characters '(', ')', '{', '}', '[' and ']',
+determine if the input string is valid.
+
+An input string is valid if:
+
+* open brackets are closed by the same type of brackets.
+* open brackets are closed in the correct order.
+* Note that an empty string is also considered valid.
+
+Example:
+
+Input: "((()))"
+Output: True
+
+Input: "[()]{}"
+Output: True
+
+Input: "({[)]"
+Output: False
+
+
+```python
+class Solution:
+  def isValid(self, s):
+    # TODO::
+
+assert False, Solution.isValid("()(){(())")
+assert True, Solution.isValid("")
+assert True, Solution.isValid("([{}])()")
+```