Question

359. Logger Rate Limiter

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Description

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 1:

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

 

Constraints:

• 0 <= timestamp <= 109
• Every timestamp will be passed in non-decreasing order (chronological order).
• 1 <= message.length <= 30
• At most 104 calls will be made to shouldPrintMessage.

Solutions

Solution 1

class Logger:
  def __init__(self):
    """
    Initialize your data structure here.
    """
    self.limiter = {}

  def shouldPrintMessage(self, timestamp: int, message: str) -> bool:
    """
    Returns true if the message should be printed in the given timestamp, otherwise returns false.
    If this method returns false, the message will not be printed.
    The timestamp is in seconds granularity.
    """
    t = self.limiter.get(message, 0)
    if t > timestamp:
      return False
    self.limiter[message] = timestamp + 10
    return True


# Your Logger object will be instantiated and called as such:
# obj = Logger()
# param_1 = obj.shouldPrintMessage(timestamp,message)

class Logger {

  private Map<String, Integer> limiter;

  /** Initialize your data structure here. */
  public Logger() {
    limiter = new HashMap<>();
  }

  /**
     Returns true if the message should be printed in the given timestamp, otherwise returns
     false. If this method returns false, the message will not be printed. The timestamp is in
     seconds granularity.
   */
  public boolean shouldPrintMessage(int timestamp, String message) {
    int t = limiter.getOrDefault(message, 0);
    if (t > timestamp) {
      return false;
    }
    limiter.put(message, timestamp + 10);
    return true;
  }
}

/**
 * Your Logger object will be instantiated and called as such:
 * Logger obj = new Logger();
 * boolean param_1 = obj.shouldPrintMessage(timestamp,message);
 */

/**
 * Initialize your data structure here.
 */
var Logger = function () {
  this.limiter = {};
};

/**
 * Returns true if the message should be printed in the given timestamp, otherwise returns false.
    If this method returns false, the message will not be printed.
    The timestamp is in seconds granularity. 
 * @param {number} timestamp 
 * @param {string} message
 * @return {boolean}
 */
Logger.prototype.shouldPrintMessage = function (timestamp, message) {
  const t = this.limiter[message] || 0;
  if (t > timestamp) {
    return false;
  }
  this.limiter[message] = timestamp + 10;
  return true;
};

/**
 * Your Logger object will be instantiated and called as such:
 * var obj = new Logger()
 * var param_1 = obj.shouldPrintMessage(timestamp,message)
 */