different-ways-to-add-parentheses

#include <vector>
#include <string>
using namespace std;

class Solution {
public:
vector<int> diffWaysToCompute(string input) {
vector<int> result;
for (int i = 0; i < input.size(); i++)
{
if (input[i] == '+' || input[i] == '-' || input[i] == '*')
{
vector<int>left = diffWaysToCompute(input.substr(0, i));
vector<int>right = diffWaysToCompute(input.substr(i + 1));
for (int j = 0; j < left.size(); j++)
for (int k = 0; k < right.size(); k++)
{
if (input[i] == '+')
result.push_back(left[j] + right[k]);
else if (input[i] == '-')
result.push_back(left[j] - right[k]);
else
result.push_back(left[j] * right[k]);
}
}
}
if (result.empty())
result.push_back(atoi(input.c_str()));
return result;
}
};