题目描述：
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: "((()))", "(()())", "(())()", "()(())", "()()()"
这题没做出来，惭愧。
solution：
void dfs(vector<string> &result,string str,int left,int right) { if(left > right) return; if (left == 0 && right == 0) { result.push_back(str); return; } if(left > 0) dfs(result, str+"(", left-1, right); if(right > 0) dfs(result, str+")", left, right-1); } vector<string> generateParenthesis(int n) { vector<string> res; if(n < 1) return res; dfs(res, "", n, n); return res; }
原文链接：http://blog.csdn.net/linhuanmars/article/details/19873463
原文：http://www.cnblogs.com/gattaca/p/4354700.html