Return all root-to-leaf path sums

Q: Return all root-to-leaf path sums

This question evaluates competency in binary tree traversal and path-state accumulation, focusing on the ability to compute sums along root-to-leaf paths while handling edge cases like empty trees and negative values.

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Question

Problem

You are given the root of a binary tree where each node contains an integer value (may be negative).

Return an array/list containing the sum of values along every path from the root to a leaf (a leaf is a node with no children).

Input

root : root node of a binary tree.

Output

A list of integers, where each integer is the sum of one root-to-leaf path.
The order of sums can be any consistent traversal order (e.g., DFS order).

Examples

Tree:

Root-to-leaf sums are:

5→4 = 9
5→8→11 = 24
5→8→4 = 17 Output (one valid): [9, 24, 17]

Single node -3 → output [-3]

Constraints (typical interview assumptions)

Number of nodes: up to ~10^4
Node values fit in 32-bit signed integer

Notes

If the tree is empty, return an empty list.