Token Bucket Rate Limiter

Implement a token bucket rate limiter for an HTTP request stream.

The token bucket works as follows:

• The bucket has a maximum capacity of capacity tokens
• Tokens refill continuously at rate tokens per second
• Each incoming request consumes 1 token
• If the bucket has at least 1 token when a request arrives, the request is allowed and 1 token is consumed
• If the bucket is empty, the request is denied
• The bucket starts full (at capacity tokens)

Implement the TokenBucket class:

• __init__(self, rate: float, capacity: int) — initializes the bucket with the given refill rate and capacity
• isRequestAllowed(self, timestamp: float) -> bool — given the timestamp (in seconds) of an incoming request, return True if the request is allowed, False otherwise

isRequestAllowed must run in O(1) time and space.

Example 1:

Input: rate = 1.0, capacity = 1, requests = [0.0]

Output: [True]

Explanation: Bucket starts full with 1 token. The request at t=0.0 consumes it — allowed.

Example 2:

Input: rate = 1.0, capacity = 1, requests = [0.0, 0.5]

Output: [True, False]

Explanation: First request consumes the only token. At t=0.5, only 0.5 tokens have refilled — not enough.

Example 3:

Input: rate = 1.0, capacity = 1, requests = [0.0, 1.0]

Output: [True, True]

Explanation: First request consumes the token. By t=1.0, exactly 1 token has refilled — second request allowed.

Constraints:

• 0 < rate <= 1e6 (tokens per second)
• 1 <= capacity <= 10^5
• Timestamps are non-decreasing floats representing seconds
• Timestamps are non-negative
• Timestamps may repeat (simultaneous requests are valid)