Path Sum
Easy
TreeDFSBinary Tree
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`.
A **leaf** is a node with no children.
**Example 1:**
```
Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
Output: true
Explanation: The path 5 → 4 → 11 → 2 sums to 22.
```
**Example 2:**
```
Input: root = [1,2,3], targetSum = 5
Output: false
```
**Example 3:**
```
Input: root = [], targetSum = 0
Output: false
```
Expected Time Complexity
O(n)
Expected Space Complexity
O(n)
Example Test Cases
Example 1
Input:
[5,4,8,11,null,13,4,7,2,null,null,null,1] 22
Output:
true
Example 2
Input:
[1,2,3] 5
Output:
false