Different Ways to Add Parentheses

241. Different Ways to Add Parentheses

Total Accepted: 13500 Total Submissions: 43882 Difficulty: Medium

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]

 (M) Unique Binary Search Trees II (M) Basic Calculator (H) Expression Add Operators

 

class Solution {
public:
    vector<int> diffWaysToCompute(string input) {
        vector<int> res;
        int input_size = input.size();
        for(int i=0;i<input_size;i++){
            if(!isdigit(input[i])){
                vector<int> res1 = diffWaysToCompute(input.substr(0,i));
                vector<int> res2 = diffWaysToCompute(input.substr(i+1));
                for(auto num1 : res1){
                    for(auto num2:res2){
                        switch(input[i]){
                            case '+' : res.push_back(num1+num2) ;break;
                            case '-' : res.push_back(num1-num2) ;break;
                            case '*' : res.push_back(num1*num2) ;break;
                        }
                    }
                }
            }
        }
        if(res.empty()){
            res.push_back(stoi(input));
        }
        return res;
    }
};