Sum Root to Leaf Numbers
You are given the root of a binary tree containing digits from 0 to 9.
Each root-to-leaf path represents a number formed by concatenating the digits along the path.
Return the total sum of all root-to-leaf numbers.
A leaf is a node with no children.
Example 1
Input
root = [1,2,3]
Output
25
Explanation
There are two root-to-leaf paths:
1 → 2 = 12
1 → 3 = 13
Therefore:
12 + 13 = 25
Example 2
Input
root = [4,9,0,5,1]
Output
1026
Explanation
The root-to-leaf numbers are:
4 → 9 → 5 = 495
4 → 9 → 1 = 491
4 → 0 = 40
Therefore:
495 + 491 + 40 = 1026
Constraints
Hints:
Hint 1
Build the number represented by the current root-to-node path while traversing the tree.
Hint 2
When you reach a leaf, add the number formed by that root-to-leaf path to the total sum.
Author & Technical Reviewer
Technically reviewed by: ExamAdda Technical Review Team
Technical Reviewers, ExamAdda
Software engineers at ExamAdda who check every article's definitions, complexity claims and code examples before and after publishing.
Published
Aug 19, 2026
Last updated
Aug 20, 2026
Content Verification Methodology
Definitions and complexity claims were checked against authoritative computer-science references. Code examples were compiled and tested with standard, boundary and edge-case inputs.
Expected Output