24. Generate Parentheses FROM Leetcode

题目

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:

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

频度： 4

解题之法

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