待解决)leetcode 路径和 dfs 线序遍历

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5
             / \
            4   8
           /   / \
          11  13  4
         /  \    / \
        7    2  5   1

return

[
   [5,4,11,2],
   [5,8,4,5]
]

1。下面的搜索总超时，可能我写的不好

 1 /**
 2  * Definition for binary tree
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     ArrayList<ArrayList<Integer>> list=new ArrayList<ArrayList<Integer>>();
12      ArrayList<Integer> arry=new ArrayList<Integer>();
13      
14     public List<List<Integer>> pathSum(TreeNode root, int sum) {
15         
16         if(root==null) return (List)list;
17         if(root.right==null&&root.left==null)
18         {
19             if(sum==root.val)
20             {
21             
22             list.add(new ArrayList(arry));
23             }
24         }
25        
26            arry.add(root.val);
27         pathSum(root.right,sum-root.val);
28       
29         
30         pathSum(root.left,sum-root.val);
31         
32         
33         return (List)list;
34         
35        
36        
37         
38         
39     }
40     
41     
42     
43 }
View Code

 

iew Co
 
 

 

posted @ 2014-07-11 19:25  hansongjiang8  阅读(239)  评论(0)  编辑  收藏  举报