LeetCode 22. Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

For example, given n = 3, a solution set is:

"((()))", "(()())", "(())()", "()(())", "()()()"

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

void generateParenthesis(int left, int right, vector<string>& res, string path) {
if(left == 0 && right == 0) {
res.push_back(path);
return;
}
if(left > 0)
generateParenthesis(left-1, right, res, path + '(');
if(right > left)
generateParenthesis(left, right-1, res, path + ')');
}

vector<string> generateParenthesis(int n) {
vector<string> res;
string path = "";
generateParenthesis(n, n, res, path);
return res;
}

}
int main(void) {
    vector<string> res = generateParenthesis(3);
    for(int i = 0; i < res.size(); ++i) {
        cout << res[i] << endl;
    }
}