359. Logger Rate Limiter

📝 Problem Details

• Title: 359. Logger Rate Limiter
• Link: https://leetcode.com/problems/logger-rate-limiter/
• Difficulty: Easy
• Tags/Categories: Hashing Design

design a logger that receives a stream of messages and their timestamps each unique message should only be printed at most every 10 seconds (a message printed at time t will prevent other identical messages from being printed until 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

💡 Explanation of Solution

Hashmap for Storing Message Timestamps

- maintain a hashmap (unordered_map<string,int>) where:
	- key = message string
	- value = earliest timestamp when this message was last seen
- when a new message arrives:
	- if the message is not in the hashmap, insert it with the current timestamp and return true
	- if the message is in the hashmap:
		- check if the current timestamp >= stored_timestamp + 10, update the timestamp and return true
		- otherwise, return false

⌛ Complexity Analysis

Time Complexity: O(1)
Space Complexity: O(n)

💻 Implementation of Solution

class Logger {
private:
    unordered_map<string, int> messageTimestamp;
public:
    Logger() {}
    
    bool shouldPrintMessage(int timestamp, string message) {
        if (messageTimestamp.find(message) == messageTimestamp.end() || 
            timestamp >= messageTimestamp[message] + 10) {
            messageTimestamp[message] = timestamp;
            return true;
        }
        return false;
    }
};
/**
 * Your Logger object will be instantiated and called as such:
 * Logger* obj = new Logger();
 * bool param_1 = obj->shouldPrintMessage(timestamp,message);
 */