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Return all file paths via DFS | NVIDIA Coding Question

Quick Overview

This question evaluates understanding of tree traversal and depth-first search along with competence in handling hierarchical data structures and constructing full file paths.

Return all file paths via DFS

Company: NVIDIA

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: easy

Interview Round: Technical Screen

You are given an in-memory representation of a file system as a tree. Each node has: - `name` (string) - `isFile` (boolean) - `children` (list of nodes, empty for files) The root node represents the root directory (e.g., name `"/"` or `"root"`). Write a function that returns **all full paths to files** in the file system. Paths should be constructed by joining directory names with `/`. Notes: - Only files should appear in the output (not directories). - The order of returned paths does not matter. Example: - root - a - b.txt (file) - c - d.md (file) - e.log (file) Output could be: - `root/a/b.txt` - `root/a/c/d.md` - `root/e.log` Implement the function using DFS.

Quick Answer: This question evaluates understanding of tree traversal and depth-first search along with competence in handling hierarchical data structures and constructing full file paths.

You are given an in-memory file system represented as a tree. Each node is a dictionary with three fields: `name` (string), `isFile` (boolean), and `children` (list of child nodes, empty for files). Write a function that returns all full paths to file nodes in the tree. A full path is built by joining node names with `/` from the root down to each file. Only files should appear in the result, not directories. Use depth-first search (DFS) to traverse the tree. For consistent evaluation, return the paths in DFS preorder, following the order of each node's `children` list from left to right. Special path rule: if the root node's name is `/`, then a child named `etc` should produce `/etc`, not `//etc`.

Constraints

The total number of nodes is between 0 and 100000.
Each file node has an empty `children` list.
Node names are non-empty strings; the root name may be `/` or any directory name such as `root`.

Examples

Input: {'name': 'root', 'isFile': False, 'children': [{'name': 'a', 'isFile': False, 'children': [{'name': 'b.txt', 'isFile': True, 'children': []}, {'name': 'c', 'isFile': False, 'children': [{'name': 'd.md', 'isFile': True, 'children': []}]}]}, {'name': 'e.log', 'isFile': True, 'children': []}]}

Expected Output: ['root/a/b.txt', 'root/a/c/d.md', 'root/e.log']

Explanation: DFS visits `a` before `e.log`, then `b.txt`, then `c/d.md`, so the file paths are returned in that order.

Input: None

Expected Output: []

Explanation: An empty file system has no file paths.

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Return all file paths via DFS

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