Given the root of a binary tree where each node contains a digit in the range 0 to 9, compute the sum of all numbers formed by root-to-leaf paths. Each path from the root to a leaf forms a number by concatenating the digits along the path. Return the sum of all such numbers.
Example 1
Input: TreeNode(7, TreeNode(2, None, TreeNode(6)), TreeNode(5))
Output: 726 + 75 = 801
Explanation: Paths: 7->2->6 forms 726, 7->5 forms 75. Sum = 801.
Example 2
Input: TreeNode(3, TreeNode(1, TreeNode(4)), TreeNode(9, None, TreeNode(8)))
Output: 314 + 398 = 712
Explanation: Paths: 3->1->4 forms 314, 3->9->8 forms 398. Sum = 712.
Constraints
Case 1
Input: TreeNode(2, TreeNode(0), TreeNode(3, TreeNode(1), None))
Expected: 20 + 231 = 251
Case 2
Input: TreeNode(8, TreeNode(7, None, TreeNode(5)), None)
Expected: 875
Case 3
Input: TreeNode(1, TreeNode(9), TreeNode(0, TreeNode(2), TreeNode(3)))
Expected: 19 + 102 + 103 = 224