Software Engineer · Online Assessment · Coding

Anthropic — Software Engineer ✅ Passed

Level: Senior-Level

Round: Online Assessment · Type: Coding · Difficulty: 7/10 · Duration: 60 min · Interviewer: Neutral

Topics: Data Structures, Hash Table, Design

Location: San Francisco Bay Area

Interview date: 2025-12-28

Summary

Round 1: Coding

Implement a simple cloud storage service that allows users to store files, duplicate existing files, and query file sizes.

Details

Implement a simple cloud storage service that allows users to store files, duplicate existing files, and query file sizes.

The system should support the following operations:

---

Operation 1

boolean addFile(String name, int size)

Adds a new file to the storage system.

• name represents the file name.
• size specifies the file size in bytes.

Rules:

• If a file with the same name already exists, the operation should fail.
• Return true if the file is successfully added.
• Return false if the operation fails.

---

Operation 2

boolean copyFile(String nameFrom, String nameTo)

Creates a copy of an existing file.

• The file located at nameFrom should be duplicated and stored under the name nameTo.

Rules:

• The operation fails if nameFrom does not correspond to an existing file or refers to a directory.
• The operation also fails if a file already exists with the name nameTo.
• Return true if the copy operation succeeds.
• Return false otherwise.

---

Operation 3

int getFilesize(String name)

Returns the size of the specified file.

Rules:

• If the file exists, return its size in bytes.
• If the file does not exist, return -1.

---

Constraints

• Each file name name is a non-empty string and may contain any visible ASCII characters, including /.
• The system does not maintain a directory hierarchy; every file name is treated independently.
• The total number of operations will not exceed 100,000.
• File sizes fit within a 32-bit signed integer.

Example

` Input: ["InMemoryDB", "setData", "setData", "getData", "getData", "deleteData", "deleteData"] [[], ["A", "B", "E"], ["A", "C", "F"], ["A", "B"], ["A", "D"], ["A", "B"], ["A", "D"]]

Output: [null, null, null, "E", "", true, false]

Explanation:

InMemoryDB db = new InMemoryDB(); db.setData("A", "B", "E"); // Returns null. Database state: {"A": {"B": "E"}} db.setData("A", "C", "F"); // Returns null. Database state: {"A": {"C": "F", "B": "E"}} db.getData("A", "B"); // Returns "E". db.getData("A", "D"); // Returns "", since there is no value of field "D". db.deleteData("A", "B"); // Returns true. Database state: {"A": {"C": "F"}} db.deleteData("A", "D"); // Returns false. Database state: {"A": {"c": "F"}} `

Solution

` from typing import List, Optional

class InMemoryDB: def init(self): # The main map: key -> (field -> value) self.db = {}

def setData(self, key: str, field: str, value: str) -> None:
    if key not in self.db:
        self.db[key] = {}
    self.db[key][field] = value

def getData(self, key: str, field: str) -> str:
    if key not in self.db:
        return ""

    fields = self.db[key]
    value = fields.get(field)
    return value if value is not None else ""

def deleteData(self, key: str, field: str) -> bool:
    if key not in self.db:
        return False

    fields = self.db[key]
    if field in fields:
        del fields[field]
        
        # If the record is empty after removal, remove the key entirely
        if not fields:
            del self.db[key]
        return True
    return False

`