leetcode/Generate_Parentheses at master · zhengdanwei/leetcode · GitHub

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class Solution {
public:
    string tmp;
    vector<string> result;
    int stnum;
    int leftnum;

    void dfs(){
        if (leftnum==0 && stnum==0){
            result.push_back(tmp);
            return;
        }

        if (leftnum>0){
            leftnum--;
            stnum++;
            tmp.push_back('(');
            dfs();
            tmp.pop_back();
            stnum--;
            leftnum++;
        }

        if(stnum>0){
            stnum--;
            tmp.push_back(')');
            dfs();
            tmp.pop_back();
            stnum++;
        }
    }

    vector<string> generateParenthesis(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        tmp="";
        result.clear();
        stnum=0;
        leftnum=n;
        dfs();
        return result;
    }
};