[Leetcode] Path Sum II

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 /**
 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     public List<List<Integer>> pathSum(TreeNode root, int sum) {
12          List<List<Integer>> result=new ArrayList<List<Integer>>();
13         List<Integer> tmp=new ArrayList<Integer>();
14         dfs(result,tmp,sum,root,0);
15         return result;
16     }
17 
18     private void dfs(List<List<Integer>> result, List<Integer> tmp, int sum, TreeNode root, int curSum) {
19         // TODO Auto-generated method stub
20         if(root==null)
21             return;
22         if(root.left==null&&root.right==null){
23             if(curSum+root.val==sum){
24                 tmp.add(root.val);
25                 result.add(new ArrayList<Integer>(tmp));
26                 tmp.remove(tmp.size()-1);
27                 return;
28             }
29             return;
30         }
31         tmp.add(root.val);
32         dfs(result,tmp,sum,root.left,curSum+root.val);
33         dfs(result,tmp,sum,root.right,curSum+root.val);
34         tmp.remove(tmp.size()-1);
35     }
36 }

 

posted @ 2014-11-16 03:16  Phoebe815  阅读(94)  评论(0)  编辑  收藏  举报