## Tree - 129. Sum Root to Leaf Numbers

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129. Sum Root to Leaf Numbers

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.

Note: A leaf is a node with no children.

Example:

``````Input: [1,2,3]
1
/ \
2   3
Output: 25
Explanation:
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Therefore, sum = 12 + 13 = 25.
``````

go：

``````/**

* Definition for a binary tree node.
* type TreeNode struct {
*     Val int
*     Left *TreeNode
*     Right *TreeNode
* }
*/
func sumNumbers(root *TreeNode) int {
var res int
if root == nil {
return res
}

recursive(root, root.Val, &res)

return res
}

func recursive(node *TreeNode, sum int, res *int) {
if node.Left == nil && node.Right == nil {
*res += sum
}

if node.Left != nil {
recursive(node.Left, sum * 10 + node.Left.Val, res)
}

if node.Right != nil {
recursive(node.Right, sum * 10 + node.Right.Val, res)
}
}
``````