257. Binary Tree Paths

• Easy, Topics, Companies

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

Solution

• Enumerate all DFS paths
• For what I know so far the DFS will use backtracking to traverse the hole tree

1. Choice: either go left or right at any given node
2. Constraint: If there is no other node to visit from the current node, then go back
3. Goal: If its a valida path store that node into the path