How should I practice Configurable Per-Client Token Buckets?

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

Is Configurable Per-Client Token Buckets associated with Snowflake?

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

Configurable Per-Client Token Buckets

Snowflake● HardFULLTIMEPHONE SCREEN

Learn

Problem statement

Simulate tiered per-client token-bucket rate limiting. The built-in default tier starts with capacity 1 and refill rate 1 token per second. Process commands in nondecreasing integer timestamp order:

CONFIG time tier capacity refill creates or replaces a tier. Before replacing an existing tier, refill every client currently assigned to it through time using the old rate, then clamp its tokens to the new capacity. A capacity increase does not grant extra tokens.
ASSIGN time client tier assigns a known tier and resets that client's bucket to the tier's full capacity at time. An unknown tier returns INVALID without changing state.
UNASSIGN time client assigns the client to default and resets its bucket to the current default capacity.
REQUEST time client cost creates an unseen client on default, refills through time, and returns ALLOW after spending cost tokens when enough exist; otherwise it returns REJECT.

Refill is elapsedSeconds * refill, capped at capacity. Return one result string per command; successful configuration and assignment commands return OK.

Function

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

Examples

Example 1

operations = ["CONFIG 0 gold 5 2","ASSIGN 0 alice gold","REQUEST 0 alice 3","REQUEST 1 alice 3","REQUEST 1 alice 2","UNASSIGN 2 alice","REQUEST 2 alice 1"]return = ["OK","OK","ALLOW","ALLOW","REJECT","OK","ALLOW"]

Alice uses the gold bucket until unassignment resets her to the default tier.

Example 2

operations = ["REQUEST 0 bob 1","CONFIG 1 default 3 1","REQUEST 1 bob 3","REQUEST 3 bob 3"]return = ["ALLOW","OK","REJECT","ALLOW"]

Reconfiguration preserves Bob's refilled token balance rather than filling the larger bucket.

Constraints

1 <= operations.length <= 10000
Timestamps are nonnegative, nondecreasing, and fit in signed 64-bit integers.
1 <= capacity, refill, cost <= 10^9.
Tier and client names are nonempty alphanumeric strings.
All intermediate token arithmetic fits in signed 64-bit integers.