How should I practice Client Stock Position Operations?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Optiver phone screen problems in FastPrep.

Is Client Stock Position Operations associated with Optiver?

FastPrep tags this as a Optiver phone screen coding practice problem when the problem catalog has that company and stage context.

Problem · Hash Table

● Medium

OptiverFULLTIMEPHONE SCREEN

Process every command in operations in order. Each client starts with a position of zero shares in every symbol.

BUY:client:symbol:quantity: add quantity shares to that client-symbol position and output the resulting quantity as a decimal string.
SELL:client:symbol:quantity: if the position contains at least quantity shares, subtract them and output the resulting quantity. Otherwise, leave the position unchanged and output REJECTED.
POSITION:client:symbol: output the current quantity, or 0 if that position has never been traded.

Return one output for every command. Positions belonging to different clients or symbols are independent.

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

operations = ["BUY:alice:AAPL:10","BUY:alice:AAPL:5","SELL:alice:AAPL:8","POSITION:alice:AAPL"]return = ["10","15","7","7"]

Alice's AAPL position grows to 15, then a successful sale reduces it to 7.

operations = ["BUY:bob:MSFT:4","SELL:bob:MSFT:5","POSITION:bob:MSFT","POSITION:bob:GOOG"]return = ["4","REJECTED","4","0"]

Bob cannot sell five MSFT shares while holding four, so the rejected sale leaves the position unchanged. An unseen symbol has position zero.

operations = ["BUY:alice:NVDA:3","BUY:bob:NVDA:6","SELL:alice:NVDA:3","POSITION:alice:NVDA","POSITION:bob:NVDA"]return = ["3","6","0","0","6"]

Alice's and Bob's NVDA positions are independent. Alice sells her entire position while Bob continues to hold six shares.

1 <= operations.length <= 100000
Every operation is exactly one of the documented command forms.
Each client and symbol is 1 to 24 ASCII letters, digits, underscores, or hyphens.
1 <= quantity <= 1000000000 for BUY and SELL.
Every resulting position fits in a signed 64-bit integer.