Is Binary Tree Paths easy or hard?

Binary Tree Paths is classified as an Easy problem. The main concept is performing a DFS traversal while building strings representing root-to-leaf paths, which makes it a common introductory problem for practicing binary tree recursion.

How to solve Binary Tree Paths in O(n)?

Perform a DFS traversal starting from the root while maintaining the current path. Append the node value to the path as you move deeper. When a leaf node is encountered, add the completed path string to the results. Since each node is processed once, the overall complexity stays O(n).

What is the best approach for Binary Tree Paths?

Depth-First Search (DFS) using recursion is the most common approach. You traverse from the root to every leaf while building a path string along the way. When a leaf node is reached, the constructed path is added to the result. This method visits each node once and runs in O(n) time.

What data structure is used in Binary Tree Paths?

The core data structure is a binary tree. The solution typically uses recursion (implicit stack) or an explicit stack for DFS traversal, along with a list or array to store the resulting path strings.

What is the time complexity of Binary Tree Paths?

The time complexity is O(n) because each node in the binary tree is visited exactly once during the DFS traversal. Additional string construction happens along the traversal path, but it remains proportional to the number of nodes overall.

Binary Tree Paths Python or Java solution approach?

Both Python and Java solutions typically use recursive DFS. The function receives the current node and the path string so far. If the node is a leaf, the path is added to the result list; otherwise, recursion continues with the left and right children.

Is Binary Tree Paths asked at Google, Amazon, or Meta interviews?

Binary tree traversal problems like Binary Tree Paths appear frequently in interviews at companies such as Amazon, Google, and Meta. The question tests understanding of DFS traversal, recursion, and path construction within tree structures.

Description Solution Video 9:24

257. Binary Tree Paths

Easy69.5% acceptance8 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

Asked at 8 companies

Capital One Revolut Apple

Google Meta Amazon Microsoft Bloomberg

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9:24

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257. Binary Tree Paths

Asked at 8 companies

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