Design a rate limiter system that begins with a specified capacity (limit) indicating the maximum number of requests allowed within a certain time interval (ttl, unit: Millisecond). When a new request arrives, return true if it is accepted under the current limit. Otherwise, return false.

Implement the RateLimiter class:

• RateLimiter(int ttl, int limit) Initializes the rate limiter with a time-to-live window ttl in milliseconds and a maximum limit for the number of requests allowed in that time frame.

• boolean allowRequest() Checks if a new request can be served based on recent requests within the ttl window.

Example 1:

Input: (Assuming the interval for each request is 100ms)

["RateLimiter","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest"]

[[1000,5],[],[],[],[],[],[],[],[],[],[],[]]

Output: [null, true, true, true, true, true, false, false, false, false, false, true]

Explanation:

• RateLimiter rateLimiter = new RateLimiter(1000, 5); // Initialize with ttl = 1000 ms and limit = 5.
• rateLimiter.allowRequest(); // Returns true. (t = 0ms)
• rateLimiter.allowRequest(); // Returns true. (t = 100ms)
• rateLimiter.allowRequest(); // Returns true. (t = 200ms)
• rateLimiter.allowRequest(); // Returns true. (t = 300ms)
• rateLimiter.allowRequest(); // Returns true. (t = 400ms)
• rateLimiter.allowRequest(); // Returns false, as the limit of 5 is hit within the last 1000 ms. (t = 500ms)
• rateLimiter.allowRequest(); // Returns false. (t = 600ms)
• rateLimiter.allowRequest(); // Returns false. (t = 700ms)
• rateLimiter.allowRequest(); // Returns false. (t = 800ms)
• rateLimiter.allowRequest(); // Returns false. (t = 900ms)
• rateLimiter.allowRequest(); // Returns true, as the oldest request (t = 0ms) has expired. (t = 1000ms)

Example 2:

Input: (Assuming the interval for each request is 300ms)

["RateLimiter","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest","allowRequest"]

[[1000,5],[],[],[],[],[],[],[],[],[],[],[]]

Output: [null, true, true, true, true, true, true, true, true, true, true]

Explanation: Since all 10 requests were sent at a rate slower than the rate limiter, they should all be allowed.