Total File System Size with Path Filter | Dataford Interview Questions

Given a file system structure of directories and files with sizes, return the total size of files; follow-up: add a path parameter and return only the size underneath that path (e.g. total_size(file_system, "/home")).

Asked in the tech screen (post 6375931, same author) stage. Candidate explained but did not finish the follow-up. Reported follow-ups: handle path lookup, such as "/var/log/wifi.log" or "var/".

Input and Output

Represent a directory as a dictionary whose values are subdirectories or files. Represent a file by its integer size. Given a valid absolute path, return the sum of all file sizes at or below that path. A file path returns its own size. The root path is /.

Constraints

The file system is a nested dictionary structure.
Directory values are dictionaries and file values are nonnegative integers.
The path is absolute, valid, and identifies the root, a directory, or a file.
Path components are separated by /; repeated or trailing separators may be present.
The total number of files and directories is at most 10^5.

Function Signature

def total_size(file_system, path):

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Problem