implement-router

Design a data structure that can efficiently manage data packets in a network router. Each data packet consists of the following attributes:

source: A unique identifier for the machine that generated the packet.

destination: A unique identifier for the target machine.

timestamp: The time at which the packet arrived at the router.

Implement the Router class:

Router(int memoryLimit): Initializes the Router object with a fixed memory limit.

memoryLimit is the maximum number of packets the router can store at any given time.

If adding a new packet would exceed this limit, the oldest packet must be removed to free up space.

bool addPacket(int source, int destination, int timestamp): Adds a packet with the given attributes to the router.

A packet is considered a duplicate if another packet with the same source, destination, and timestamp already exists in the router.

Return true if the packet is successfully added (i.e., it is not a duplicate); otherwise return false.

int[] forwardPacket(): Forwards the next packet in FIFO (First In First Out) order.

Remove the packet from storage.

Return the packet as an array [source, destination, timestamp].

If there are no packets to forward, return an empty array.

int getCount(int destination, int startTime, int endTime):

Returns the number of packets currently stored in the router (i.e., not yet forwarded) that have the specified destination and have timestamps in the inclusive range [startTime, endTime].

Note that queries for addPacket will be made in increasing order of timestamp.

Example 1:

Input:

["Router", "addPacket", "addPacket", "addPacket", "addPacket", "addPacket", "forwardPacket", "addPacket", "getCount"]

[[3], [1, 4, 90], [2, 5, 90], [1, 4, 90], [3, 5, 95], [4, 5, 105], [], [5, 2, 110], [5, 100, 110]]

Output:

[null, true, true, false, true, true, [2, 5, 90], true, 1]

Explanation

Router router = new Router(3); // Initialize Router with memoryLimit of 3.

router.addPacket(1, 4, 90); // Packet is added. Return True.

router.addPacket(2, 5, 90); // Packet is added. Return True.

router.addPacket(1, 4, 90); // This is a duplicate packet. Return False.

router.addPacket(3, 5, 95); // Packet is added. Return True

router.addPacket(4, 5, 105); // Packet is added, [1, 4, 90] is removed as number of packets exceeds memoryLimit. Return True.

router.forwardPacket(); // Return [2, 5, 90] and remove it from router.

router.addPacket(5, 2, 110); // Packet is added. Return True.

router.getCount(5, 100, 110); // The only packet with destination 5 and timestamp in the inclusive range [100, 110] is [4, 5, 105]. Return 1.

Example 2:

Input:

["Router", "addPacket", "forwardPacket", "forwardPacket"]

[[2], [7, 4, 90], [], []]

Output:

[null, true, [7, 4, 90], []]

Explanation

Router router = new Router(2); // Initialize Router with memoryLimit of 2.

router.addPacket(7, 4, 90); // Return True.

router.forwardPacket(); // Return [7, 4, 90].

router.forwardPacket(); // There are no packets left, return [].

Constraints:

2 <= memoryLimit <= 105

1 <= source, destination <= 2 * 105

1 <= timestamp <= 109

1 <= startTime <= endTime <= 109

At most 105 calls will be made to addPacket, forwardPacket, and getCount methods altogether.

queries for addPacket will be made in increasing order of timestamp.

implement-router

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