Leetcode 129: 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.

 

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     public int val;
 5  *     public TreeNode left;
 6  *     public TreeNode right;
 7  *     public TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public int SumNumbers(TreeNode root) {
12         var result = new int[1] {0};
13         DFS(root, 0, result);
14         return result[0];
15     }
16     
17     private void DFS(TreeNode node, int cur, int[] result)
18     {
19         if (node == null) return;
20         
21         if (node.left == null && node.right == null)
22         {
23             result[0] += cur + node.val;
24         }
25         
26         if (node.left != null) DFS(node.left, (cur + node.val) * 10, result);
27         if (node.right != null) DFS(node.right, (cur + node.val) * 10, result);
28     }
29 }

 

posted @ 2017-11-20 05:06  逸朵  阅读(125)  评论(0)  编辑  收藏  举报