Sum of Root To Leaf Binary Numbers
You need to compute the sum of the binary numbers represented by each roottoleaf path in a binary tree, where each node has a value of 0 or 1.
Here’s an approach to solve this problem:
 Use DepthFirst Search (DFS) to traverse the tree.
 Maintain a current number, representing the binary number constructed from the root to the current node.
 When reaching a leaf node, add the current number to the sum.
 Return the total sum.


Explanation:
 The function
dfs
recursively traverses the tree.  In each call, it updates
current_number
by leftshifting its binary representation and adding the current node’s value (this corresponds to adding a new bit to the binary number).  If the current node is a leaf, the function returns the current number.
 If the current node has children, the function calls itself recursively on the left and right children, and returns the sum of the results.
 Finally, the main function calls
dfs
starting from the root, with an initial current number of 0, and returns the result.