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:
"((()))", "(()())", "(())()", "()(())", "()()()"
本题是括号匹配输出，利用迭代输出。
代码如下：
class Solution { public: void unguarded_generate(vector<string> &result, string curr, int m, int n){ if (m == 0 && n == 0){ result.push_back(curr); } else{ if (m != 0){ cout << curr << endl; unguarded_generate(result, curr + "(", m - 1, n); } if (m < n && n != 0){ cout << curr << endl; unguarded_generate(result, curr + ")", m, n - 1); } } } vector<string> generateParenthesis(int n) { vector<string> ret; if (n > 0){ unguarded_generate(ret, string(), n, n); } return ret; } };
原文：http://www.cnblogs.com/Scorpio989/p/4545075.html