Create parsing-a-boolean-expression.py

Author: kamyu104

Python/parsing-a-boolean-expression.py

@@ -0,0 +1,30 @@
+# Time:  O(n)
+# Space: O(n)
+
+class Solution(object):
+    def parseBoolExpr(self, expression):
+        """
+        :type expression: str
+        :rtype: bool
+        """
+        def parse(expression, i):
+            if expression[i[0]] not in "&|!":
+                result = expression[i[0]] == 't'
+                i[0] += 1
+                return result
+            op = expression[i[0]]
+            i[0] += 2
+            stk = []
+            while expression[i[0]] != ')':
+                if expression[i[0]] == ',': 
+                    i[0] += 1
+                    continue
+                stk.append(parse(expression, i))
+            i[0] += 1
+            if op == '&':
+                return all(stk)
+            if op == '|':
+                return any(stk)
+            return not stk[0]
+
+        return parse(expression, [0])