LetCode 22. 括号生成

static int x=[](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();


class Solution {
public:
    vector<string> generateParenthesis(int n) {
        vector<string> res;
        generateParenthesis(res, "", n, n);
        return res;
    }
    
    void generateParenthesis(vector<string>& res, string temp, int left, int right){
        if (left > right)
            return;
        if (left <= 0 && right <= 0){
            res.push_back(temp);
            return;
        }
        
        if (left > 0)generateParenthesis(res, temp + '(', left - 1, right);
        if (right> 0)generateParenthesis(res, temp + ')', left, right - 1);
    }
};