LeetCode(22)-Generate Parentheses

问题描述：

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:

"((()))", "(()())", "(())()", "()(())", "()()()"

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问题分析：

深度优先遍历DFS，能加“（”就加，能加“）”就加“）”

问题求解：

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

这题没有思路，以上答案参考讨论组里的，比较容易懂。