路径和 二叉树 leecode

题目不难，很快ac,纯粹靠手感。https://oj.leetcode.com/problems/sum-root-to-leaf-numbers/

 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     private int sum=0;

12     public int sumNumbers(TreeNode root) {

13         if(root==null) return 0;

14         

15         

16       

17         sum(root,""+root.val);

18         return sum;

19         

20     }

21     public void sum(TreeNode root,String s)

22     {

23         

24         if(root.left==null&&root.right==null)

25         {

26             sum+=Integer.parseInt(s);

27         }

28         else

29         {

30             if(root.left!=null) sum(root.left,s+root.left.val);

31             if(root.right!=null) sum(root.right,s+root.right.val);

32             

33             

34             

35         }

36         

37         

38         

39     }

40     

41 }