LoggerRateLimiter.java

package LeetCodeJava.HashTable;

// https://leetcode.ca/2016-11-23-359-Logger-Rate-Limiter/
// https://leetcode.com/problems/logger-rate-limiter/description/

import java.util.HashMap;
import java.util.Map;

/**
 *
 * 359. Logger Rate Limiter
 * 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.
 *
 */

public class LoggerRateLimiter {

    // V0
    // IDEA : HASHMAP
    // TODO : validate below
    class Logger {

        private Map<String, Integer> limiter;

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

        public boolean shouldPrintMessage(int timestamp, String message) {
            if (!this.limiter.containsKey(message)){
                this.limiter.put(message, timestamp+10);
                return true;
            }
            int canPrintTime = this.limiter.get(message);
            if (timestamp > canPrintTime){
                return true;
            }
            return false;
        }

    }

    // V1
    class Logger_1 {

        private Map<String, Integer> limiter;

        /** Initialize your data structure here. */
        public Logger_1() {
            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;
        }
    }

    // V2

}