0359. Logger Rate Limiter.py

# 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 <= 10^9
# Every timestamp will be passed in non-decreasing order (chronological order).
# 1 <= message.length <= 30
# At most 104 calls will be made to shouldPrintMessage.


# Hash table
# Space O(M), M is the size of all incoming messages
class Logger:
    def __init__(self):
        self.dic = {}

    # Time O(1)
    def shouldPrintMessage(self, timestamp: int, message: str) -> bool:
        if message not in self.dic:
            self.dic[message] = timestamp
            return True

        if timestamp - self.dic[message] >= 10:
            self.dic[message] = timestamp
            return True
        else:
            return False