Leetcode: Different Ways to Add Parentheses

Different Ways to Add Parentheses



Similar Problems:


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]

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.


## Blog link: https://code.dennyzhang.com/different-ways-to-add-parentheses
class Solution:
    def diffWaysToCompute(self, input):
        res = []
        for i, ch in enumerate(input):
            if ch in "+-*":
                l1 = self.diffWaysToCompute(input[:i])
                l2 = self.diffWaysToCompute(input[i+1:])
                for num1 in l1:
                    for num2 in l2:
                        if ch == '+': res.append(num1+num2)
                        if ch == '-': res.append(num1-num2)
                        if ch == '*': res.append(num1*num2)
        return res if res !=[] else [int(input)]
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