leetcode--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:

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

[java] view plain copy

1. public class Solution {  
2.     public List<String> generateParenthesis(int n) {  
3.         List<String> result = new ArrayList<String>();  
4.         solve(0, 0, n, result, "");  
5.         System.out.println(result);  
6.         return result;  
7.     }  
8.   
9.     void solve(int left,int right,int n,List<String> result,String str){  
10.         if(left<right) return;//left括号数目一定要比右边多  
11.         if(left==n && right==n){//如果左右括号数目相等则添加到list  
12.             result.add(str);  
13.             return;  
14.         }  
15.         if(left==n){//左括号已满，只能添加右括号  
16.             solve(left, right+1, n, result, str+")");  
17.             return;  
18.         }  
19.         solve(left+1, right, n, result, str+"(");//继续添加左括号  
20.         solve(left, right+1, n, result, str+")");//继续添加右括号  
21.     }  
22. }  

原文链接http://blog.csdn.net/crazy__chen/article/details/45577891