0022. Generate Parentheses.cpp

class Solution
{
public:
    vector<string> generateParenthesis(int n)
    {
        vector<string> ans;
        
        if (n == 0)
        {
            ans.push_back("");
        }
        else
        {
            for (int i = 0; i < n; ++i)
            {
                for (string l : generateParenthesis(i))
                {
                    for (string r : generateParenthesis(n - 1 - i))
                    {
                        ans.push_back("(" + l + ")" + r);
                    }
                }
            }
        }
        
        return ans;
    }
};