[アルゴリズム]LeetCode-Loger Rate Limiter

LeetCode - Logger Rate Limiter
問題の説明

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.

I/O例
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
せいげんじょうけん

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.

Solution

import java.util.HashMap;

class Logger {

    /** Initialize your data structure here. */

    private HashMap<String, Integer> workTimestamps;

    public Logger() {
        workTimestamps = new HashMap<String, Integer>();
    }

    /**
     * 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) {

        if (workTimestamps.containsKey(message)) {
            int lastTimestamp = workTimestamps.get(message);
            if (timestamp < lastTimestamp) {
                return false;
            }
        }

        workTimestamps.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);
 */