leetcode Generate Parentheses

采用递归算法

代码

class Solution {
public:
    vector<string> generateParenthesis(int n) {
        
        string tempResult;
        vector<string> result;
        generateParenthesisHelper(result, tempResult, n, n);
    
        return result;
    }
    
    
    void generateParenthesisHelper(vector<string> &result, string & tempResult ,int left, int right)
    {
        if(left>right)
            return ;
        if(left==0&&right==0)
        {
            result.push_back(tempResult);
            return ;
        }
        
        if(left>0)
        {
            tempResult.push_back('(');
            generateParenthesisHelper(result, tempResult, left-1, right);
            tempResult.pop_back();
        }
        
        if(right>0)
        {
            tempResult.push_back(')');
            generateParenthesisHelper(result, tempResult, left, right-1);
            tempResult.pop_back();
            
        }
        
        
    }
};