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.
base是父节点的和。每条路径结果在叶子节点产生。
/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public int sumNumbersHelper(TreeNode root, int base) { if (root == null) { return 0; } base = base * 10 + root.val; if (root.left == null && root.right == null) { return base; } return sumNumbersHelper(root.left, base) + sumNumbersHelper(root.right, base); } public int sumNumbers(TreeNode root) { return sumNumbersHelper(root, 0); } }
原文：http://www.cnblogs.com/23lalala/p/3517440.html