Add User With Capacity

EasyPython

Problem

A Dropbox team maintains a shared storage limit. Implement ADD_USER(user_id, capacity) to register a user with a requested storage capacity.

The operation succeeds only when the user ID is not already registered, the capacity is positive, and the team's total assigned capacity does not exceed max_capacity. On success, add the user and return True. On failure, leave the user mapping unchanged and return False.

Formal Specification

Implement add_user(users, user_id, capacity, max_capacity).

users is a dictionary mapping user IDs to assigned capacities.
user_id is a string.
capacity and max_capacity are integers measured in gigabytes.
The function mutates users only after all validation checks pass.
Return a Boolean indicating whether the user was added.

The existing dictionary may contain valid users, and its assigned capacities count toward the team's limit.

Constraints

0 <= len(users) <= 10^5
1 <= capacity <= 10^9
0 <= max_capacity <= 10^14
Every existing capacity is positive
User IDs are non-empty strings

Function Signature

def add_user(users, user_id, capacity, max_capacity):

A Dropbox team maintains a shared storage limit. Implement ADD_USER(user_id, capacity) to register a user with a requested storage capacity.

Formal Specification

Implement add_user(users, user_id, capacity, max_capacity).

users is a dictionary mapping user IDs to assigned capacities.
user_id is a string.
capacity and max_capacity are integers measured in gigabytes.
The function mutates users only after all validation checks pass.
Return a Boolean indicating whether the user was added.

The existing dictionary may contain valid users, and its assigned capacities count toward the team's limit.