# LeetCode Different Ways to Add Parentheses

LeetCode Different Ways to Add Parentheses

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]`

Credits:
Special thanks to @mithmatt for adding this problem and creating all test cases.

```class Solution {
private:
int operate(int a, int b, char c) {
switch (c) {
case '+':return a + b;
case '-':return a - b;
case '*':return a*b;
}
}
public:
vector<int> diffWaysToCompute(string input) {
int n = input.size();
vector<int> ans;
bool found = false;
for (int i = 0; i < n; ++i) {
if (input[i] == '+' || input[i] == '-' || input[i] == '*') {
found = true;
vector<int> lefts = diffWaysToCompute(input.substr(0, i));
vector<int> rights = diffWaysToCompute(input.substr(i + 1));
for (int j = 0; j < lefts.size(); ++j) {
for (int k = 0; k < rights.size(); ++k) {
ans.push_back(operate(lefts[j], rights[k], input[i]));
}
}
}
}
if (!found)return{ atoi(input.c_str()) };
return ans;
}
};
```