Vaccination Drive
In order to curb the spread of the novel COVID-19 virus, the citizens of Hackerland need to be vaccinated on priority. There are center_nodes vaccination centers in Hackerland, where each center has a status denoted by status[i]:
• Centers with a shortage of vaccines have status 1.
• Those with sufficient vaccines have status 2.
• Those with a surplus have status 3.

Vac cines can be transferred from centers with a surplus to centers with a deficit. There is a network of bidirectional roads between centers where the ith road is between cities center_from[i] and center_to[i]. Each road takes 1 unit of time to traverse. Find the minimum time in which all deficient centers can receive a supply of vaccines from some surplus center.

Note: • Surplus centers have an inexhaustible supply of vaccines.
• Multiple surplus centers can ship their surplus simultaneously.
• Multiple deliveries from a single surplus center can leave simultaneously.
• Vaccines are only shipped from centers with status 3 to centers with status 1. Status 2 centers do nothing. Show More

Optimal Points Selection

Given a set of n distinct points on the x-axis, choose k of them such that the minimum distance between any two chosen points is as large as possible. Find this maximum possible minimum distance.
Example
Consider n = 5, k = 3, and x = [1, 4, 2, 9, 8].
In the optimal solution, one of the possible selections of points is [1, 4, 8]. Here,
The distance between 1 and 4 = abs(1 - 4) = 3
The distance between 1 and 8 = abs(1 - 8) = 7
The distance between 4 and 8 = abs(4 - 8) = 4
The minimum amongst them is 3, which is the maximum possible.
Function Description
Complete the function maximizeMinimumDistance in the editor below.
maximizeMinimumDistance has the following parameters:
int x[n]: the x-coordinates of points
int k: the number of points to choose
Returns
int: the maximum possible minimum distance between any 2 of the chosen points. Show More

Optimal Points Selection

Given a set of n distinct points on the x-axis, choose k of them such that the minimum distance between any two chosen points is as large as possible. Find this maximum possible minimum distance.
Example
Consider n = 5, k = 3, and x = [1, 4, 2, 9, 8].
In the optimal solution, one of the possible selections of points is [1, 4, 8]. Here,
The distance between 1 and 4 = abs(1 - 4) = 3
The distance between 1 and 8 = abs(1 - 8) = 7
The distance between 4 and 8 = abs(4 - 8) = 4
The minimum amongst them is 3, which is the maximum possible.
Function Description
Complete the function maximizeMinimumDistance in the editor below.
maximizeMinimumDistance has the following parameters:
int x[n]: the x-coordinates of points
int k: the number of points to choose
Returns
int: the maximum possible minimum distance between any 2 of the chosen points. Show More

Drone Delivery Optimization – Amazon's Challenge

In Amazon's vast distribution network, drones are essential for delivering packages. These drones have varying capacities, ranging from 1 to 10⁹. Each j-th drone has a carrying capacity of j.
Problem Statement
Amazon needs to dispatch n packages, where the weight of the i-th package is given by the array pack[i].During peak delivery times, only two drones are available for transport. These drones must alternate in their duties. This means:
- If Drone 1 delivers the i-th package,
- Then Drone 2 must deliver the (i+1)-th package, and so on.

However, not all drones can carry all packages — some packages might be too heavy for a particular drone.
To address this issue, Amazon can replace certain packages with others of a different (lighter) weight to ensure successful delivery.

Task
Your task is to determine the minimum number of package replacements needed, such that all packages can be successfully delivered by some pair of drones, alternating turns.
You are allowed to choose any two drones with any capacity.

Example
n = 4
pack = [3, 1, 3, 2] Show More

GetMinimalCost

One of the products listed on Amazon Ecommerce is available in n sizes as indicated in the array size. The category manager recognizes that some of the sizes are repetitive and do not provide a good user experience. To make the best use of inventory, the product should be available in distinct sizes. The size of the ith product, size[i], can be increased by one unit for an amount in the cost array, cost[i].

Given the arrays size and cost for the product, find the minimal total cost in order to make all the sizes distinct.

Example
Given n = 4, size = [2, 3, 3, 2] and cost = [2, 4, 5, 1].

It costs 7 units to make the prices distinct.
We can also adjust size[1] to 5, which costs cost[1] * (5 - size[1]) = 8, and size[3] to 4, which costs cost[3] * (4 - size[3]) = 2.
Therefore, the total cost is 8 + 2 = 10.

However, 7 is the minimum cost required to make all sizes distinct. Show More

User Transaction Report for 2023
In the digital age, payment systems are essential for online transactions. For businesses managing these systems, understanding user activity is key to optimizing services and enhancing engagement.
A development team is tasked with creating a report that shows:
The total number of transactions made by each user.
The total sum of those transactions.
Analyzing t hese patterns will help identify highly active users and those who may need additional engagement.

Requirements
The output of the report should include the following columns:
- email: The email address of the user.
- total_transactions: The total number of transactions made by the user.
- total_amount: The total value of the transactions (rounded to two decimal places, including trailing
zeros if needed, e.g., 500.00).
The results should be sorted in ascending order by email.
Note:
Only include transactions that occurred in the year 2023.

Schema
Table: users
id (INT): The identifier of the user
email (VARCHAR(255)): The email address of the user

Table: transactions
user_id (INT): The reference to the user
amount (DECIMAL(5,2)): The amount of the transaction
created_at (VARCHAR(19)): The date and time of the transaction
Foreign Key: user_id references users(id) Show More

Roman Numerals

You are given an array of integers. Your task is to convert each integer into its Roman numeral equivalent.

The following table contains some reference values for converting between Arabic (standard integers) and Roman numerals:

Arabic - Roman
1 - I
4 - IV
5 - V
9 - IX
10 - X
40 - XL
50 - L
90 - XC
100 - C
400 - CD
500 - D
900 - CM
1000 - M

Example
Input: n umbers = [1, 49, 23]
Output: ["I", "XLIX", "XXIII"]

Explanation:

1 is "I"

49 is 40 + 9 → "XL" + "IX" = "XLIX"

23 is 10 + 10 + 3 → "X" + "X" + "III" = "XXIII"

Function Description
Complete the function romanizer in the editor below.

romanizer has the following parameters:
int numbers[n]: an array of integers

Returns
string[n]: an array of strings that represent the integers as their Roman numeral equivalents.

Constraints
1 ≤ n ≤ 1000
1 ≤ numbers[i] ≤ 1000 Show More

Hackerrank developers want to deploy an application on a set of exactly k servers with different vulnerabilities. They have an option to choose the k servers from a sequence of n servers where vulnerability[i] represents the vulnerability of the ith server.

The vulnerability of the chosen k servers is defined as the maximum vulnerability amongst any of the chosen servers. To avoid congestion, t hey would like to choose a subsequence of k servers such that no two adjacent servers are chosen as part of the k servers.

Given an array vulnerability and an integer k, find the minimum possible vulnerability of the chosen servers such that the above condition is respected.

Example
Given n = 4, k = 2 and vulnerability = [2, 3, 5, 9], only 3 subsequences of k = 2 non-adjacent servers exist:

[2, 5] - max = 5
[3, 9] - max = 9
[2, 9] - max = 9

Report 5 as the answer.

Function Description
Complete the function getMinVulnerability in the editor below.

getMinVulnerability has the following parameters:
int vulnerability[n]: An array of integers
int k: the length of the subsequences to form

Returns
int: the minimum value returned by the max function for all valid subsequences

Constraints
1 <= n <= 10^5
1 <= k <= (n + 1) / 2 Show More

FindMaximumWeights
Amazon's fulfillment centers handle packages of various weights, and they need to optimize their sorting process.
Given an array weight that denotes the weights of n packages, the goal is to create the lexicographically maximal resulting array sorted in non-increasing order using the following operations:
1. Discard the first package from the current weight array.
2. A dd the first element to the resulting array, then remove it along with the next k (a fixed constant) elements from the current array.
Operation 2 can also be applied when fewer than k elements remain after the current element; in that case, the entire remaining array is removed.

The resulting array must have packages arranged in non-increasing weight order.
Given an array weight of size n and an integer k, find the lexicographically maximal resulting array sorted by non-increasing order of weight that can be obtained. Show More

GetMaxThroughput

The developers at Amazon are working on optimizing database query times. There are n host servers, where the throughput of the i-th host server is given by host_throughput[i].
These servers are grouped into clusters of size three. The throughput of a cluster, denoted as cluster_throughput, is defined as the median of the three servers’ throughput values. Each host server can be part of at most one cluster, and some servers may remain unused.

The total system throughput, called system_throughput, is the sum of the throughputs of all the clusters formed. The task is to find the maximum possible system throughput.

Note:
The median of a cluster of three host servers is the 2nd highest throughput when the three values are sorted in ascending or descending order.

Example:
Input:
n = 5
host_throughput = [2, 3, 4, 3, 4]

Output:
The maximum number of clusters that can be formed is 1, and two host servers will remain unused. Show More