Solve 241 with python(dp)

Author: illuz

solutions/241.Different_Ways_to_Add_Parentheses/AC_dp_n2.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+# Author:      illuz <iilluzen[at]gmail.com>
+# File:        AC_dp_n2.py
+# Create Date: 2015-10-23 14:38:55
+# Usage:       AC_dp_n2.py
+# Descripton:
+
+class Solution(object):
+    def diffWaysToCompute(self, input):
+        """
+        :type input: str
+        :rtype: List[int]
+        """
+        return self.helper(input, {})
+
+    def helper(self, input, seen):
+        if input in seen:
+            return seen[input]
+        if input.isnumeric():
+            return [int(input)]
+        res = []
+        for i, c in enumerate(input):
+            if c in '-+*':
+                L = self.helper(input[:i], seen)
+                R = self.helper(input[i+1:], seen)
+                res += [l+r if c == '+' else l-r if c == '-' else l*r
+                for l in L
+                for r in R]
+        seen[input] = res
+        return res
+
+s = Solution()
+print(s.diffWaysToCompute('2*3+4*5'))