Sum Root to Leaf Numbers

 

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number 123.

Find the total sum of all root-to-leaf numbers.

For example,

    1

   / \

  2   3

 

The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.

» Solve this problem

 

 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     int sum;

12     public int sumNumbers(TreeNode root) {

13         // Start typing your Java solution below

14         // DO NOT write main() function

15         sum = 0;

16         int cur = 0;

17         add(root,cur);

18         return sum;

19     }

20     public void add(TreeNode node, int cur){

21         if(node == null){

22             return;

23         }

24         cur = cur * 10 + node.val;

25         if(node.left == null && node.right == null){//leaves

26             sum += cur;

27         }

28         add(node.left,cur);

29         add(node.right,cur);

30     }

31 }