[Apple Question][LeetCode] Logger Rate Limiter

Problem: Design a logger system that receives a stream of messages along with their timestamps. Each unique message should only be printed at most every 10 seconds (i.e. a message printed at timestamp t will prevent other identical messages from being printed until timestamp t + 10).

All messages will come in chronological order. Several messages may arrive at the same timestamp.

Implement the Logger class:

• Logger() Initializes the logger object.
• bool shouldPrintMessage(int timestamp, string message) Returns true if the message should be printed in the given timestamp, otherwise returns false.

Example:

Input
["Logger", "shouldPrintMessage", "shouldPrintMessage", "shouldPrintMessage", "shouldPrintMessage", "shouldPrintMessage", "shouldPrintMessage"]
[[], [1, "foo"], [2, "bar"], [3, "foo"], [8, "bar"], [10, "foo"], [11, "foo"]]
Output
[null, true, true, false, false, false, true]

Explanation
Logger logger = new Logger();
logger.shouldPrintMessage(1, "foo");  // return true, next allowed timestamp for "foo" is 1 + 10 = 11
logger.shouldPrintMessage(2, "bar");  // return true, next allowed timestamp for "bar" is 2 + 10 = 12
logger.shouldPrintMessage(3, "foo");  // 3 < 11, return false
logger.shouldPrintMessage(8, "bar");  // 8 < 12, return false
logger.shouldPrintMessage(10, "foo"); // 10 < 11, return false
logger.shouldPrintMessage(11, "foo"); // 11 >= 11, return true, next allowed timestamp for "foo" is 11 + 10 = 21

Approach: Problem looks straight forward. We can maintain a hash with key as message and value as timestamp to solve this problem. Have a look at implementation to understand the approach.

Implementation in C#:

public class Logger 

{

    public Logger() 

    {

        this.messageTimestampDict = new Dictionary<string, int>();

    }

    

    public bool ShouldPrintMessage(int timestamp, string message) 

    {

        if (this.messageTimestampDict.ContainsKey(message) && timestamp - this.messageTimestampDict[message] < 10)

        {

            return false;

        }

        this.messageTimestampDict[message] = timestamp;

        return true;  

    }

    

    Dictionary<string, int> messageTimestampDict;

}

Complexity: O(1)