Leetcode 22. Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

For example, given n = 3, a solution set is:

[
  "((()))",
  "(()())",
  "(())()",
  "()(())",
  "()()()"
]

题目链接：https://leetcode.com/problems/generate-parentheses/

这一题借鉴了国外某位同志的思路，递归真的太巧妙了

class Solution {
public:
    vector generateParenthesis(int n) {
        vector res;
        addpar(res, "", n, 0);
        return res;
    }
    void addpar(vector &v, string str, int n, int m){
        if(n==0 && m==0) {
            v.push_back(str);
            return;
        }
        if(m > 0)
        {
            addpar(v,str+")",n,m-1);
        }
        if(n > 0)
        {
            addpar(v,str+"(",n-1,m+1);
        }
    }
};