# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    '''
    Time Complexity: O(n)
    Space Complexity: O(n)
    where, n is the number of nodes in the tree
    Solved in 12 mins, all by yourself! Good job!
    '''
    def sumRootToLeaf(self, root: Optional[TreeNode]) -> int:
        def traverse(node):
            if not node:
                return []
            children = traverse(node.left) + traverse(node.right)
            return [str(node.val)] if not children else [str(node.val) + child for child in children]
        return sum(int(x,2) for x in traverse(root))