151. Design Logger Message Printer

Design Logger Message Printer

Design a logger system that processes a stream of messages along with their timestamps.

Each unique message can be printed at most once within any 10 second window. That means if a message is printed at timestamp t, the same message cannot be printed again before timestamp t + 10.

All incoming messages are provided in chronological order. It is also possible for multiple messages to share the same timestamp.

Class

MessageLogger

Methods

`MessageLogger()`

Initializes the logger system.

`boolean canPrintMessage(int timestamp, String message)`

Returns true if the given message is allowed to be printed at timestamp.
Returns false if the same message was printed in the last 10 seconds.
If a message is printed at timestamp t, then the next valid timestamp for that message becomes t + 10.

Rules

Messages are evaluated in non-decreasing order of timestamp.
Multiple messages may arrive at the same timestamp.
The decision for a message depends only on its own previous printed timestamps.

Constraints

0 ≤ timestamp ≤ 10^9
1 ≤ message.length ≤ 30
Timestamps are always provided in non-decreasing order.
At most 10^4 calls are made to canPrintMessage.

Examples

Example 1

MessageLogger logger = new MessageLogger();

logger.canPrintMessage(timestamp = 1, message = "foo") returns true

The message "foo" has not been printed before.
The next valid timestamp for "foo" becomes 11.

logger.canPrintMessage(timestamp = 2, message = "bar") returns true

The message "bar" is new.
The next valid timestamp for "bar" becomes 12.

logger.canPrintMessage(timestamp = 3, message = "foo") returns false

3 < 11, so "foo" is still restricted.

logger.canPrintMessage(timestamp = 8, message = "bar") returns false

8 < 12, so "bar" cannot be printed yet.

logger.canPrintMessage(timestamp = 10, message = "foo") returns false

10 < 11, so "foo" is still blocked.

logger.canPrintMessage(timestamp = 11, message = "foo") returns true

11 ≥ 11, so "foo" can be printed again.
The next valid timestamp becomes 21.

Example 2

MessageLogger logger = new MessageLogger();

logger.canPrintMessage(timestamp = 5, message = "alpha") returns true

First occurrence of "alpha".

logger.canPrintMessage(timestamp = 5, message = "beta") returns true

Different message, evaluated independently.

logger.canPrintMessage(timestamp = 14, message = "alpha") returns false

The next valid timestamp for "alpha" is 15.

logger.canPrintMessage(timestamp = 15, message = "alpha") returns true

15 meets the required delay.