Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are +
, -
and *
.
Example 1
Input: "2-1-1"
.
((2-1)-1) = 0 (2-(1-1)) = 2
Output: [0, 2]
Example 2
Input: "2*3-4*5"
(2*(3-(4*5))) = -34 ((2*3)-(4*5)) = -14 ((2*(3-4))*5) = -10 (2*((3-4)*5)) = -10 (((2*3)-4)*5) = 10
Output: [-34, -14, -10, -10, 10]
class Solution(object): def diffWaysToCompute(self, input): """ :type input: str :rtype: List[int] A: (2*3)-4*5 ((2*3)-4)*5=>1 (2*3)-(4*5)=>2 B: 2*(3-4)*5 (2*(3-4))*5=>1 2*((3-4)*5)=>2 """ import re tokens = re.split('(D)', input) nums = map(int, tokens[::2]) ops = map({'+': operator.add, '-': operator.sub, '*': operator.mul}.get, tokens[1::2]) def build(lo, hi): if lo == hi: return [nums[lo]] ans = [] for i in range(lo, hi): for a in build(lo, i): for b in build(i+1, hi): ans.append(ops[i](a, b)) return ans return build(0, len(ops))
re.split("(D)", "2+3-1")
['2', '+', '3', '-', '1']