Given the root of a binary tree, return all root-to-leaf paths in any order.

A leaf is a node with no children.

Example 1:

Input: root = [1,2,3,null,5]
Output: ["1->2->5","1->3"]

Example 2:

Input: root = [1]
Output: ["1"]

Constraints:

• The number of nodes in the tree is in the range [1, 100].
• -100 <= Node.val <= 100

1. Find a leaf: A leaf is a node with no children.
2. If either the left or right child exists:
   • Perform DFS recursively with the child as the new root.
3. If neither left nor right child exists:
   • Append the path to the answer array.