Determine if tree has path sum
Company: Chicago
Role: Data Scientist
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Technical Screen
## Problem
Given the `root` of a binary tree and an integer `targetSum`, return `true` if the tree has a **root-to-leaf** path such that adding up all the values along the path equals `targetSum`. Otherwise, return `false`.
- A **leaf** is a node with no children.
- A **root-to-leaf** path starts at the root and ends at any leaf.
## Input
- `root`: binary tree node with fields `val`, `left`, `right`
- `targetSum`: integer
## Output
- Boolean indicating whether such a path exists.
## Example
For a tree with root-to-leaf path values `[5,4,11,2]` and `targetSum = 22`, return `true` because `5 + 4 + 11 + 2 = 22`.
## Notes / Constraints (assumptions)
- Node values and `targetSum` may be negative.
- You should handle an empty tree (`root = null`).
## Task
Implement a function (e.g., in Python) to solve this problem efficiently.
Quick Answer: This question evaluates understanding of binary tree data structures and traversal techniques, along with the ability to accumulate and track root-to-leaf path sums while correctly handling edge cases such as empty trees and negative values.