[Leetcode] sum root to leaf numbers

Question

Given a Binary Tree Containing digits from0-9Only, each root-to-leaf path cocould 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.

Answer

Recursive solution with tree

/** * 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) {        if(root==null){            return 0;        }        return sum(root,0);    }        public int sum(TreeNode node,int parentVal){        int sum=0;        int temp=parentVal*10+node.val;        if(node.left==null&&node.right==null){            sum=temp;        }        if(node.left!=null){            sum+=sum(node.left,temp);        }        if(node.right!=null){            sum+=sum(node.right,temp);        }        return sum;    }} 

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