# [Programming Problem] Sum Root to Leaf Numbers

```You are given the root of a binary tree containing digits from 0 to 9 only.   Each root-to-leaf path in the tree represents a number.   For example, the root-to-leaf path 1 -> 2 -> 3 represents the number 123. Return the total sum of all root-to-leaf numbers. Test cases are generated so that the answer will fit in a 32-bit integer.   A leaf node is a node with no children.   Example 1: Input: root = [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.     Example 2: Input: root = [4,9,0,5,1] Output: 1026 Explanation: The root-to-leaf path 4->9->5 represents the number 495. The root-to-leaf path 4->9->1 represents the number 491. The root-to-leaf path 4->0 represents the number 40. Therefore, sum = 495 + 491 + 40 = 1026.```

```/** * Definition for a binary tree node. * function TreeNode(val, left, right) { * this.val = (val===undefined ? 0 : val) * this.left = (left===undefined ? null : left) * this.right = (right===undefined ? null : right) * } */ /** * @param {TreeNode} root * @return {number} */ var sumNumbers = function(root) { const sumRef = [0]; sum(root, [], sumRef); return sumRef[0]; };   var sum = function(root, path, sumRef) { if (root === null) return; if (root.left === null && root.right === null) { sumRef[0] += Number(path.join('') + root.val); return; }   sum(root.left, [...path, root.val], sumRef); sum(root.right, [...path, root.val], sumRef); }```