题目：
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
public class Solution { public int sumNumbers(TreeNode root) { return dfs(root, 0); } private int dfs(TreeNode root, int prev){ if(root == null) { return 0; } int sum = root.val + prev * 10; if(root.left == null && root.right == null) { return sum; } return dfs(root.left, sum) + dfs(root.right, sum); } }
转载于:https://www.cnblogs.com/hygeia/p/4766087.html
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