HackAJob Interview Royal Problem.

RoyalHackAJob.java

import org.junit.Assert;
import org.junit.Test;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;

/**
 * @author Richard Price-Jones
 */


public class Main {


    public static void main(String[] args) {
        /*
         * Some work here; return type and arguments should be according to the problem's requirements
         */
        Main main = new Main();
        String[] inputs = {"George VI", "William II", "Elizabeth I", "William I"};
        main.processInput(inputs);
    }

    /**
     * Process Royal Names and return as ordered String
     *
     * @param royalNames String[] RoyalNames
     * @return String RoyalNamesOrder
     */
    public String processInput(String... royalNames) {

        List<Royal> royals = new ArrayList<>();

        for (String royalName : royalNames) {
            String[] names = royalName.split(" ");
            royals.add(new Royal(names[0], names[1]));
        }

        StringBuilder stringBuilder = new StringBuilder();

        // Sort Values and appended into a string.
        royals.stream().sorted(Comparator.comparing(Royal::getName)
                .thenComparing(r -> convertRomanToInt(r.getOrdinalNumber())))
                .forEach(r -> stringBuilder.append(r.toString()).append(" "));

        return stringBuilder.toString();
    }

    /**
     * Takes a Roman number and Converts into a Integer.
     *
     * @param roman String Roman Number
     * @return Integer Converted Value
     */
    public Integer convertRomanToInt(String roman) {

        HashMap<String, Integer> roman_numerals = new HashMap<>();
        roman_numerals.put("I", 1);
        roman_numerals.put("V", 5);
        roman_numerals.put("X", 10);
        roman_numerals.put("L", 50);

        String currentValue;

        // Roman Logic
        // if Number is greater or equal than next one add to result otherwise subtract it from result.
        // 47 -> XLVII -> -10 + 50 + 5 + 1 + 1 = 47
        char[] romanArr = roman.toCharArray();
        Integer result = 0;
        for (int i = 0; i <= romanArr.length - 1; i++) {
            currentValue = String.valueOf(roman.charAt(i));
            if ((i + 1) == roman.length() || roman_numerals.get(currentValue) >= roman_numerals.get(String.valueOf(roman.charAt(i + 1)))) {
                result += roman_numerals.get(currentValue);
            } else {
                result -= roman_numerals.get(currentValue);
            }
        }
        return result;
    }
}

class Royal {

    private final String name;
    private final String ordinalNumber;


    public Royal(String name, String ordinalNumber) {
        this.name = name;
        this.ordinalNumber = ordinalNumber;
    }

    public String getName() {
        return name;
    }

    public String getOrdinalNumber() {
        return ordinalNumber;
    }

    @Override
    public String toString() {
        return this.name + " " + this.ordinalNumber;
    }
}

class TestRoyal {

    @Test
    public void testProcessInput() {

        String[] inputs = {"George VI", "William II", "Elizabeth I", "William I"};
        String expectOutput = "Elizabeth I George VI William I William II";

        Main main = new Main();
        String result = main.processInput(inputs);

        Assert.assertEquals(expectOutput, result);
    }

    @Test
    public void testConvertRomanToIntForFortySeven() {

        final String romanValueForFortySeven = "XLVII";
        final Integer expectOutput = 47;

        Main main = new Main();
        Integer result = main.convertRomanToInt(romanValueForFortySeven);

        Assert.assertEquals(expectOutput, result);
    }

    @Test
    public void testConvertRomanToIntForOne() {

        final String romanValueForOne = "I";
        final Integer expectOutput = 1;

        Main main = new Main();
        Integer result = main.convertRomanToInt(romanValueForOne);

        Assert.assertEquals(expectOutput, result);
    }
}