FastPrepCloud Storage System, Part 2: Largest Files

Cloud Storage System, Part 2: Largest Files

Ramp logoRamp● MediumNEW GRADOA
Learn

Problem statement

Your task is to implement a simple cloud storage system. All operations that should be supported are listed below.

Solving this task consists of several levels. Subsequent levels are opened when the current level is correctly solved. You always have access to the data for the current and all previous levels.

Requirements

Your task is to implement a simple cloud storage system that maps objects (files) to their metainformation. Specifically, the storage should maintain files and information about them, including each file name and size. This system is in-memory; it does not use the real filesystem.

The levels are cumulative:

  • Level 1 supports adding, retrieving, and deleting files.
  • Level 2 displays the largest files matching a prefix.
  • Level 3 adds capacity-limited users and user merging.
  • Level 4 backs up and restores a user's files.

To move to the next level, all tests at the current level must pass.

Note

The queries never call operations that produce a collision between a file name and a directory name.

FastPrep Operation-Sequence Adapter

FastPrep calls the function once with operations. Process the rows from left to right while preserving one shared storage state. Every row starts with an uppercase operation name followed by that method's string arguments.

Return one string-array row for every input operation:

  • Encode a Boolean as ["true"] or ["false"].
  • Encode an integer as one element, such as ["10"].
  • Encode None as an empty row [].
  • Return the formatted list from GET_N_LARGEST directly; an empty list is also [].

Multipart Series

Level 1: File Operations

The cloud storage system should support file manipulation.

  • add_file(self, name: str, size: int) -> bool adds a new file name to the storage. size is the amount of memory required in bytes. The operation fails if a file with the same name already exists. Return True if the file was added successfully or False otherwise. The adapter row is ["ADD_FILE", name, size]. Files added this way are owned by the unlimited admin user.
  • get_file_size(self, name: str) -> int | None returns the size of file name if it exists, or None otherwise. The adapter row is ["GET_FILE_SIZE", name].
  • delete_file(self, name: str) -> int | None deletes file name. Return the deleted file size when deletion succeeds, or None if the file does not exist. The adapter row is ["DELETE_FILE", name].

Level 2: Largest Files

Implement an operation for retrieving statistics about files with a specific prefix.

  • get_n_largest(self, prefix: str, n: int) -> list[str] returns the names of the top n largest files whose names start with prefix, formatted as ["<name_1>(<size_1>)", ..., "<name_n>(<size_n>)"].
  • Sort matching files by size in descending order. Break a size tie by file name in lexicographical ascending order.
  • If there are no matching files, return an empty list. If fewer than n files match, return all of them in the specified format.
  • The adapter row is ["GET_N_LARGEST", prefix, n].

The visible source table contains one malformed no-match call whose second argument is a file name even though the declared signature requires n: int. The judged contract follows the declared signature: n is an integer, and a prefix with no matches returns an empty row.

Function

cloudStorageLevel2(operations: String[][]) → String[][]

Examples

Example 1

operations = [["ADD_FILE","/dir1/dir2/file.txt","10"],["ADD_FILE","/dir1/dir2/file.txt","5"],["GET_FILE_SIZE","/dir1/dir2/file.txt"],["DELETE_FILE","/non-existing.file"],["DELETE_FILE","/dir1/dir2/file.txt"],["GET_FILE_SIZE","/not-existing.file"]]return = [["true"],["false"],["10"],[],["10"],[]]

The first add succeeds, the duplicate add fails, and the existing file size is 10. Deleting a missing file returns None; deleting the existing file returns 10; the final lookup again returns None.

Example 2

operations = [["ADD_FILE","/dir/file1.txt","5"],["ADD_FILE","/dir/file2","20"],["ADD_FILE","/dir/deeper/file3.mov","9"],["GET_N_LARGEST","/dir","2"],["GET_N_LARGEST","/dir/file","3"],["GET_N_LARGEST","/another_dir","3"],["ADD_FILE","/big_file.mp4","20"],["GET_N_LARGEST","/","2"]]return = [["true"],["true"],["true"],["/dir/file2(20)","/dir/deeper/file3.mov(9)"],["/dir/file2(20)","/dir/file1.txt(5)"],[],["true"],["/big_file.mp4(20)","/dir/file2(20)"]]

Prefix filtering keeps matching names only. Size is the primary order; equal sizes are ordered lexicographically. The no-match query returns an empty row.

Constraints

  • Every operation row is well formed and uses an operation available at this level.
  • Every numeric argument is a base-10 integer string whose value and all arithmetic results fit in a signed 64-bit integer.
  • File names, prefixes, and user IDs are non-empty case-sensitive strings.
  • The input never creates a collision between a file name and a directory name.
  • All users share one global file-name namespace. The admin user exists initially and has unlimited capacity.
  • Process operations in the supplied order. The storage starts empty.

More Ramp problems

See Ramp hiring insights
public String[][] cloudStorageLevel2(String[][] operations) {
  // Process the operations in order and return one result row per operation.
  // write your code here
}
operations[["ADD_FILE","/dir1/dir2/file.txt","10"],["ADD_FILE","/dir1/dir2/file.txt","5"],["GET_FILE_SIZE","/dir1/dir2/file.txt"],["DELETE_FILE","/non-existing.file"],["DELETE_FILE","/dir1/dir2/file.txt"],["GET_FILE_SIZE","/not-existing.file"]]
expected[["true"], ["false"], ["10"], [], ["10"], []]
Checking account…