# 241. Different Ways to Add Parentheses """ given a string 'expression' of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. you may return the answer in any order. the test cases are generated such that the output values fit in a 32-bit integer and the number of different results does not exceed 10^4 """ class Solution(object): def dfs(self, expression, m): if expression in m: return m[expression] if expression.isdigit(): m[expression] = int(expression) return [int(expression)] res = [] for i, j in enumerate(expression): if j in "+-*": l = self.diffWaysToCompute(expression[:i]) r = self.diffWaysToCompute(expression[i + 1 :]) res.extend(eval(str(x) + j + str(y)) for x in l for y in r) m[expression] = res return res def diffWaysToCompute(self, expression): """ :type expression: str :rtype: List[int] """ m = {} return self.dfs(expression, m) if __name__ == "__main__": obj = Solution() print(obj.diffWaysToCompute(expression="2-1-1")) print(obj.diffWaysToCompute(expression="2*3-4*5"))