Sum Root to Leaf Numbers

最新推荐文章于 2019-08-12 13:35:43 发布

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本文探讨了如何计算给定二叉树中从根节点到每个叶子节点路径所代表数字的总和。通过遍历树结构并累积路径上的数值，最终得出所有路径数字的和。

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.

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int sumNumbers(TreeNode root) {
        return sum(root, 0);
    }
    
    int sum(TreeNode root, int value){
        int res=0;
        if(root==null){
            return 0;
        }else{
            int subval=value*10+root.val;
            if((root.left!=null)||(root.right!=null)){
                res=sum(root.left, subval)+sum(root.right, subval);
            }else{
                res=subval;
            }
        return res;
        }
    }
}