227. Logger Rate Limiter

Remember the last time each message was printed. A message prints only if it is new or at least 10 seconds have passed since its last print.

Track last print per message

Keep a map message -> last printed timestamp. On shouldPrintMessage(t, msg): if msg is unseen or t - last[msg] >= 10, update last[msg] = t and return true; otherwise return false.

if msg not in last or t - last[msg] >= 10:
    last[msg] = t; return True
return False

Worked example

foo@1 → true, foo@3 → false (only 2s later), foo@10 → false (9s), foo@11 → true (10s since 1).

Complexity

• Time: O(1) per call.
• Space: O(distinct messages).

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

class Logger {
    private Map<String, Integer> last = new HashMap<>();

    public Logger() {
    }

    public boolean shouldPrintMessage(int timestamp, String message) {
        if (!last.containsKey(message) || timestamp - last.get(message) >= 10) {
            last.put(message, timestamp);
            return true;
        }
        return false;
    }
}