[LeetCode]Generate Parentheses

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:

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

回溯的方法，递归实现。

 1 class Solution {
 2 private:
 3 public:
 4     void generate(int left,int right,string s,vector<string>& result)
 5     {
 6         if(left==0 && right==0)
 7         {
 8             result.push_back(s);
 9         }
10         if(left>0)
11         {
12             generate(left-1,right,s+'(',result);
13         }
14         if(right>0 && left<right)
15         {
16             generate(left,right-1,s+')',result);
17         }
18     }
19     vector<string> generateParenthesis(int n) {
20         string s="";
21         vector<string> result;
22         generate(n,n,s,result);
23         return result;
24     }
25 };