Incremental Portfolio Totals State Store

Problem

You’re building a real-time fintech risk dashboard that monitors millions of brokerage sub-accounts grouped into “portfolios” (e.g., household, advisor book, or strategy bucket). Traders and compliance teams rely on instant portfolio totals to enforce margin rules and detect suspicious activity.

You are given an initial in-memory state with:

• account_balance: mapping account_id -> balance
• portfolio_accounts: mapping portfolio_id -> list of account_ids (each account belongs to exactly one portfolio at any time)

Then you receive a stream of actions (strings). You must process them in order and return the results of every query.

Actions

1. ADD_ACCOUNT user_id portfolio_id account_id balance
   • Create a new account with the given balance and attach it to portfolio_id.
2. UPDATE_BALANCE account_id new_balance
   • Update the account’s balance.
3. MOVE_ACCOUNT account_id from_portfolio_id to_portfolio_id
   • Move the account between portfolios.
4. QUERY_PORTFOLIO_TOTAL portfolio_id
   • Return the sum of balances of all accounts currently in that portfolio.

Task

Implement:

def process_actions(initial_state: dict, actions: list[str]) -> list[int]:

Return a list of integers containing the results of each QUERY_PORTFOLIO_TOTAL in order.

Notes / Clarifications

• Portfolio IDs and account IDs are integers in the actions, but initial_state may contain them as strings (JSON input). Your solution must handle both.
• Querying a portfolio that currently has no accounts should return 0.
• All IDs referenced in actions are valid, and MOVE_ACCOUNT always specifies the account’s current portfolio as from_portfolio_id.

Examples

Example 1

• Input:
  • initial_state = {'portfolio_accounts': {1: [10, 11]}, 'account_balance': {10: 50, 11: 70}}
  • actions = ['QUERY_PORTFOLIO_TOTAL 1', 'UPDATE_BALANCE 10 80', 'QUERY_PORTFOLIO_TOTAL 1']
• Output: [120, 150]
• Explanation: Total starts at 50+70=120. Updating account 10 from 50→80 adds +30, so total becomes 150.

Example 2

• Input:
  • initial_state = {'portfolio_accounts': {1: [10], 2: [20]}, 'account_balance': {10: 5, 20: 7}}
  • actions = ['MOVE_ACCOUNT 10 1 2', 'QUERY_PORTFOLIO_TOTAL 1', 'QUERY_PORTFOLIO_TOTAL 2']
• Output: [0, 12]
• Explanation: Moving account 10 subtracts 5 from portfolio 1 and adds 5 to portfolio 2.