ORIGINAL CODING QUESTION
Notification cooldown
Deliver the first notification for each user. Deliver another only when at least cooldown time has passed since that user’s last DELIVERED notification. Ignored notifications do not restart cooldown. Return the delivered count.
Original exercise · easy. Editorial role relevance does not imply a company has asked this question.
Input and output
n cooldown, then n pairs (timestamp,userId), in nondecreasing timestamp order.
Constraints
1 ≤ n ≤ 1000; 1 ≤ cooldown ≤ 1000; times and IDs in [0,10000].
Example 1
Input
4 3 0 1 1 1 3 1 3 2
Output
3
User 1 receives at 0 and 3; user 2 at 3.
Example 2
Input
3 2 0 1 1 1 2 1
Output
2
Ignoring time 1 does not delay time 2.
Explain your approach
Explain your time and auxiliary space complexity. Which input makes your algorithm work hardest?
Private grading inputs, expected outputs and canonical reference implementations are withheld. Authored expected outputs were cross-checked with independent reference oracles; compiler/runtime behavior still needs a verified execution provider.
Hint 1
Keep a last delivery per user.
Hint 2
Ignored events must not update it.
Hint 3
A difference equal to cooldown qualifies.
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