Generate Parentheses

Link:http://oj.leetcode.com/problems/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:

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

 1 public class Solution {
 2     public ArrayList<String> result = new ArrayList<String>();
 3 
 4     public ArrayList<String> generateParenthesis(int n) {
 5         if (n < 1)
 6             return result;
 7         result = new ArrayList<String>();
 8         String temp = "";
 9         //recursion(left,right,temp);
10         recursion(n, n, temp);
11         return result;
12     }
13 
14     public void recursion(int left, int right, String temp) {
15         if (left == 0 && right == 0) {
16             result.add(temp);
17             return;
18         }
19         if (left == 0) {
20             recursion(left, right - 1, temp + ")");
21             return;
22         }
23         if (right == 0)
24             return;
25 
26         if (left > right)
27             return;
28         recursion(left - 1 , right, temp + "(");
29         recursion(left, right - 1, temp + ")");
30     }
31 }

 

posted on 2014-05-08 00:07  Atlas-Zzz  阅读(146)  评论(0)  编辑  收藏  举报

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