sum-root-to-leaf-numbers

题目描述

Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path1->2->3which represents the number123.

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

For example,

1

/ \
2 3

The root-to-leaf path1->2represents the number12.
The root-to-leaf path1->3represents the number13.

Return the sum = 12 + 13 =25.

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {

    int sum = 0;

    public int sumNumbers(TreeNode root) {

        if(root != null) getSum(root);
        return sum;
    }

    private void getSum(TreeNode n){
        if(n.left == null && n.right == null){
            sum += n.val;
        }
        if(n.left != null){
            n.left.val += n.val * 10;
            getSum(n.left);
        }
        if(n.right != null){
            n.right.val += n.val * 10;
            getSum(n.right);
        }
    }
}