GenerateParentheses_BackTracing.cpp

vector<string>res;
class Solution {
public:
    void choose(string prix,int left,int right,int times,int num){
        if(times==num){
            string temp =prix+")";
            res.push_back(temp);
            return;
        }
        if(left<num/2){
            string temp =prix+"(";
            choose(temp,left+1,right,times+1,num);
        }
        if(right<left){
            string temp =prix+")";
            choose(temp,left,right+1,times+1,num);
        }
        
        } 
    vector<string> generateParenthesis(int n) {
        int num =n*2;
        int left =0,right=0;
        res.clear();
        if(n==0) return res;
        int times =0;
        string prix ="";
        choose(prix,left,right,times+1,num);
        return res;
    }
};