题解 | 括号生成

#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return string字符串vector
     */
    string path;
    vector<string> ret;
    int _n;
    vector<string> generateParenthesis(int n) {
        // write code here
        int left=0,right=0;
        _n=n;
        dfs(0,0);
        return ret;
    }
    void dfs(int left,int right)
    {
        if(left>=right&&left<_n)
        {
            path+="(";
            left++;
            dfs(left,right);
            left--;
            path.pop_back();
        }

        if(left>=right&&right<_n)
        {
            path+=")";
            right++;
            dfs(left,right);
            right--;
            path.pop_back();
        }

        if(left+right==2*_n)
        {
            ret.push_back(path);
        }
    }
};