LeetCode 129 Sum Root to Leaf Numbers

题目描述

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,



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.

分析

参考：Sum Root to Leaf Numbers

代码

[code]    public static int sumNumbers(TreeNode root) {
        return sumNumbers(root, 0);
    }

    static int sumNumbers(TreeNode root, int parentval) {

        if (root == null) {
            return 0;
        }

        int p = parentval * 10 + root.val;

        if (root.left == null && root.right == null) {
            return p;
        }

        return sumNumbers(root.left, p) + sumNumbers(root.right, p);
    }