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Commit04723b5

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Added tasks 3507-3510
1 parentec417ab commit04723b5

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packageg3501_3600.s3507_minimum_pair_removal_to_sort_array_i;
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// #Easy #Array #Hash_Table #Heap_Priority_Queue #Simulation #Linked_List #Ordered_Set
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// #Doubly_Linked_List #2025_04_09_Time_1_ms_(100.00%)_Space_42.96_MB_(53.67%)
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publicclassSolution {
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publicintminimumPairRemoval(int[]nums) {
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intoperations =0;
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while (!isNonDecreasing(nums)) {
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intminSum =Integer.MAX_VALUE;
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intindex =0;
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// Find the leftmost pair with minimum sum
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for (inti =0;i <nums.length -1;i++) {
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intsum =nums[i] +nums[i +1];
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if (sum <minSum) {
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minSum =sum;
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index =i;
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}
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}
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// Merge the pair at index
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int[]newNums =newint[nums.length -1];
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intj =0;
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inti =0;
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while (i <nums.length) {
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if (i ==index) {
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newNums[j++] =nums[i] +nums[i +1];
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// Skip the next one since it's merged
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i++;
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}else {
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newNums[j++] =nums[i];
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}
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i++;
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}
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nums =newNums;
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operations++;
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}
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returnoperations;
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}
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privatebooleanisNonDecreasing(int[]nums) {
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for (inti =1;i <nums.length;i++) {
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if (nums[i] <nums[i -1]) {
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returnfalse;
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}
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}
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returntrue;
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}
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}
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3507\. Minimum Pair Removal to Sort Array I
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Easy
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Given an array`nums`, you can perform the following operation any number of times:
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* Select the**adjacent** pair with the**minimum** sum in`nums`. If multiple such pairs exist, choose the leftmost one.
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* Replace the pair with their sum.
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Return the**minimum number of operations** needed to make the array**non-decreasing**.
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An array is said to be**non-decreasing** if each element is greater than or equal to its previous element (if it exists).
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**Example 1:**
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**Input:** nums =[5,2,3,1]
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**Output:** 2
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**Explanation:**
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* The pair`(3,1)` has the minimum sum of 4. After replacement,`nums = [5,2,4]`.
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* The pair`(2,4)` has the minimum sum of 6. After replacement,`nums = [5,6]`.
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The array`nums` became non-decreasing in two operations.
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**Example 2:**
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**Input:** nums =[1,2,2]
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**Output:** 0
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**Explanation:**
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The array`nums` is already sorted.
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**Constraints:**
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*`1 <= nums.length <= 50`
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*`-1000 <= nums[i] <= 1000`
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packageg3501_3600.s3508_implement_router;
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// #Medium #Array #Hash_Table #Binary_Search #Design #Ordered_Set #Queue
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// #2025_04_09_Time_137_ms_(100.00%)_Space_116.63_MB_(91.98%)
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importjava.util.ArrayList;
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importjava.util.HashMap;
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importjava.util.LinkedList;
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importjava.util.Queue;
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@SuppressWarnings("java:S135")
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publicclassRouter {
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privatefinalintsize;
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privateintcur;
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privatefinalQueue<int[]>q;
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privatefinalHashMap<Integer,ArrayList<int[]>>map;
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publicRouter(intmemoryLimit) {
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q =newLinkedList<>();
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map =newHashMap<>();
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size =memoryLimit;
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cur =0;
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}
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publicbooleanaddPacket(intsource,intdestination,inttimestamp) {
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if (map.containsKey(destination)) {
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booleanfound =false;
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ArrayList<int[]>list =map.get(destination);
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for (inti =list.size() -1;i >=0;i--) {
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if (list.get(i)[1] <timestamp) {
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break;
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}elseif (list.get(i)[0] ==source) {
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found =true;
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break;
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}
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}
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if (found) {
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returnfalse;
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}
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}
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if (map.containsKey(destination)) {
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ArrayList<int[]>list =map.get(destination);
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list.add(newint[] {source,timestamp});
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cur++;
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q.offer(newint[] {source,destination,timestamp});
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}else {
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ArrayList<int[]>temp =newArrayList<>();
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temp.add(newint[] {source,timestamp});
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cur++;
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map.put(destination,temp);
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q.offer(newint[] {source,destination,timestamp});
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}
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if (cur >size) {
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forwardPacket();
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}
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returntrue;
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}
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publicint[]forwardPacket() {
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if (q.isEmpty()) {
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returnnewint[] {};
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}
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int[]temp =q.poll();
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ArrayList<int[]>list =map.get(temp[1]);
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list.remove(0);
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if (list.isEmpty()) {
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map.remove(temp[1]);
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}
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cur--;
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returntemp;
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}
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publicintgetCount(intdestination,intstartTime,intendTime) {
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if (map.containsKey(destination)) {
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ArrayList<int[]>list =map.get(destination);
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intlower = -1;
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inthigher = -1;
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for (inti =0;i <list.size();i++) {
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if (list.get(i)[1] >=startTime) {
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lower =i;
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break;
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}
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}
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for (inti =list.size() -1;i >=0;i--) {
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if (list.get(i)[1] <=endTime) {
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higher =i;
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break;
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}
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}
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if (lower == -1 ||higher == -1) {
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return0;
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}else {
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returnMath.max(0,higher -lower +1);
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}
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}else {
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return0;
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}
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}
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}
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/*
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* Your Router object will be instantiated and called as such:
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* Router obj = new Router(memoryLimit);
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* boolean param_1 = obj.addPacket(source,destination,timestamp);
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* int[] param_2 = obj.forwardPacket();
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* int param_3 = obj.getCount(destination,startTime,endTime);
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*/
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3508\. Implement Router
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Medium
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Design a data structure that can efficiently manage data packets in a network router. Each data packet consists of the following attributes:
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*`source`: A unique identifier for the machine that generated the packet.
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*`destination`: A unique identifier for the target machine.
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*`timestamp`: The time at which the packet arrived at the router.
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Implement the`Router` class:
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`Router(int memoryLimit)`: Initializes the Router object with a fixed memory limit.
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*`memoryLimit` is the**maximum** number of packets the router can store at any given time.
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* If adding a new packet would exceed this limit, the**oldest** packet must be removed to free up space.
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`bool addPacket(int source, int destination, int timestamp)`: Adds a packet with the given attributes to the router.
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* A packet is considered a duplicate if another packet with the same`source`,`destination`, and`timestamp` already exists in the router.
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* Return`true` if the packet is successfully added (i.e., it is not a duplicate); otherwise return`false`.
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`int[] forwardPacket()`: Forwards the next packet in FIFO (First In First Out) order.
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* Remove the packet from storage.
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* Return the packet as an array`[source, destination, timestamp]`.
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* If there are no packets to forward, return an empty array.
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`int getCount(int destination, int startTime, int endTime)`:
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* 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]`.
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**Note** that queries for`addPacket` will be made in increasing order of`timestamp`.
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**Example 1:**
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**Input:**
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["Router", "addPacket", "addPacket", "addPacket", "addPacket", "addPacket", "forwardPacket", "addPacket", "getCount"]
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[[3],[1, 4, 90],[2, 5, 90],[1, 4, 90],[3, 5, 95],[4, 5, 105],[],[5, 2, 110],[5, 100, 110]]
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**Output:**
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[null, true, true, false, true, true,[2, 5, 90], true, 1]
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**Explanation**
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Router router = new Router(3); // Initialize Router with memoryLimit of 3.
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router.addPacket(1, 4, 90); // Packet is added. Return True.
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router.addPacket(2, 5, 90); // Packet is added. Return True.
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router.addPacket(1, 4, 90); // This is a duplicate packet. Return False.
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router.addPacket(3, 5, 95); // Packet is added. Return True
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router.addPacket(4, 5, 105); // Packet is added,`[1, 4, 90]` is removed as number of packets exceeds memoryLimit. Return True.
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router.forwardPacket(); // Return`[2, 5, 90]` and remove it from router.
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router.addPacket(5, 2, 110); // Packet is added. Return True.
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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.
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**Example 2:**
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**Input:**
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["Router", "addPacket", "forwardPacket", "forwardPacket"]
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[[2],[7, 4, 90],[],[]]
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**Output:**
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[null, true,[7, 4, 90],[]]
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**Explanation**
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Router router = new Router(2); // Initialize`Router` with`memoryLimit` of 2.
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router.addPacket(7, 4, 90); // Return True.
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router.forwardPacket(); // Return`[7, 4, 90]`.
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router.forwardPacket(); // There are no packets left, return`[]`.
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**Constraints:**
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* <code>2 <= memoryLimit <= 10<sup>5</sup></code>
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* <code>1 <= source, destination <= 2 * 10<sup>5</sup></code>
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* <code>1 <= timestamp <= 10<sup>9</sup></code>
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* <code>1 <= startTime <= endTime <= 10<sup>9</sup></code>
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* At most <code>10<sup>5</sup></code> calls will be made to`addPacket`,`forwardPacket`, and`getCount` methods altogether.
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* queries for`addPacket` will be made in increasing order of`timestamp`.

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