easyBacktrackingBinary TreeDfsTrees 0 views

Get All Root-to-Leaf Paths

Return every root-to-leaf path in a binary tree as a list of node values, instead of an arrow-joined string.

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

Unlike a version of this problem that formats each path as a string (e.g. "1->2->5"), here each path should be returned as its own array of node values in order, e.g. [1, 2, 5]. The final result is an array of these path arrays, e.g. [[1,2,5],[1,3]].

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]]

Example 3

Input: root = []

Output: []

Explanation: An empty tree has no root-to-leaf paths.

Constraints

  • The number of nodes in the tree is in the range [0, 100].
  • -100 <= Node.val <= 100

Follow-up

Can you solve it iteratively using an explicit stack instead of recursion?

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