challenge

Answer to an interview challenge.

• with kotlin best practices
• use assertj
• build fat jar

build with:

./gradlew clean build

run with:

cd build/libs
java -jar challengeHospital-2.0.0.jar "F,D,T,T" "P,An"

Coding challenge

Problem description

You were asked by a doctor friend to prepare for her a “Hospital simulator”, which can simulate the future patients’ state, based on their current state and a list of drugs they take. Patients can have one of these states:

• F: Fever
• H: Healthy
• D: Diabetes
• T: Tuberculosis
• X: Dead

In the “Hospital simulator” drugs are provided to all patients. It is not possible to target a specific patient. This is the list of available drugs:

• As: Aspirin
• An: Antibiotic
• I: Insulin
• P: Paracetamol

Drugs can change patients’ states. They can cure, cause side effects or even kill a patient if not properly prescribed. Drugs effects are described by the following rules:

• Aspirin cures Fever;
• Antibiotic cures Tuberculosis;
• A sick patient not receiving the right medicines remains sick, if not explicitly mentioned otherwise;
• Insulin prevents diabetic subject from dying, does not cure Diabetes;
• If insulin is mixed with antibiotic, healthy people catch Fever;
• Paracetamol cures Fever;
• Paracetamol kills subject if mixed with aspirin;
• With a probability of 1/1,000,000 the Flying Spaghetti Monster shows his noodly power and resurrects a dead patient (Dead becomes Healthy).

While applying the rules, please keep in mind that:

• During one simulation a patient can change his state only once (only one rule can be applied).
• Rules causing Death take precedence over others.

Input Parameter 1 List of patients' health status codes, separated by a comma. e.g. “D,F,F” means we have 3 patients, one with diabetes and two with fever. Parameter 2 List of drugs codes, separated by a comma, e.g. “As,I” means patients will be treated with Aspirin and Insulin. Output The result should be sent to stdout. It should be a comma separated string with number of patients with a given state, following the format: F:NP,H:NP,D:NP,T:NP,X:NP Where:

• F, H, D, T, X are patients’ health status codes;
• NP is a number of patients for a given state; E.g. “F:0,H:2,D:0,T:0,X:1” means there are two healthy patients and one that is dead.

Examples

1. Input: "D,D" "" Output: "F:0,H:0,D:0,T:0,X:2" (diabetic patients die without insulin)

$ java -cp hospital-simulator.jar com.edgelab.hospital.Application D,D
F:0,H:0,D:0,T:0,X:2

2. Input: "F" "P" Output: "F:0,H:1,D:0,T:0,X:0" (paracetamol cures fever)

$ java -cp hospital-simulator.jar com.edgelab.hospital.Application F P
F:0,H:1,D:0,T:0,X:0