Amazon Interview Question for Software Engineer / Developers

Country: United States
Interview Type: In-Person

Comment hidden because of low score. Click to expand.
of 4 vote

public class RomanNumber {

    private final static TreeMap<Integer, String> romanMap = new TreeMap<Integer, String>();

    static {

        romanMap.put(1000, "M");
        romanMap.put(900, "CM");
        romanMap.put(500, "D");
        romanMap.put(400, "CD");
        romanMap.put(100, "C");
        romanMap.put(90, "XC");
        romanMap.put(50, "L");
        romanMap.put(40, "XL");
        romanMap.put(10, "X");
        romanMap.put(9, "IX");
        romanMap.put(5, "V");
        romanMap.put(4, "IV");
        romanMap.put(1, "I");


    public final static String convertToRoman(int number) {
        int l =  romanMap.floorKey(number);
        if ( number == l ) {
            return romanMap.get(number);
        return romanMap.get(l) + convertToRoman(number-l);
    public static void main(String[] args) {
    	for (int i = 1; i<= 110; i++) {
            System.out.println(i+"\t =\t "+RomanNumber.convertToRoman(i));


- mohsin May 26, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 1 vote

public String intToRoman(int num) {
        int numbers[] = new int[]{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
        String roman[] = new String[]{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
        int index = 0, x = num;
        StringBuilder result = new StringBuilder();
        while(x != 0){
            int count = x / numbers[index];
            if(count > 0){
                while(count > 0){
                x = x % numbers[index];
        return result.toString();

- AJ June 24, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

To write up a method for converting integer to Roman numerals is relatively easy.

But I wasn't confident in how to design a class for it. 
'Cause there didn't seem like much.

I just answered, "It does a simple conversion that we can make it static and put it in an utility class". 

Any thoughts?

- CoderLonely May 25, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

Not everyone is a big fan of statics. Especially cause of it getting in the way of unit testing.

I would put this simply this way.

public sealed class RomanNumeric
       public RomanNumeric()

       public string GetRomanNumeric(int x)

       //In case of C#, a syntactic sugar for converting int to roman
       public static implicit operator string (int x)

- Frank Q May 25, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

//Writing the function in Javascript ...

function romanize(num){
var romanDecimal ={M:1000,CM:900,D:500,CD:400,C:100,XC:90,L:50,XL:40,X:10,IX:9,V:5,IV:4,I:1};
var i;
var roman = '';

for (i in romanDecimal){
while(num >= romanDecimal[i]){
roman = roman+i;
num = num - romanDecimal[i];
return roman;

for ( var i=1 ; i <=10 ; ++i )
document.getElementById("demo").innerHTML+= i+"\t"+romanize(i)+"<br/>";

- Nidhi Sinha July 13, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

Here's a "scalable" solution in Java. It's "scalable" as long as you don't mind tons of "M"s for very large numbers! :)

public static String intToRoman(int num){
     * Symbol	I	V	X	L	C	D	M
     *  Value	1	5	10	50	100	500	1,000
     * 1776 as MDCCLXXVI
     * 1954 as MCMLIV
     * 1990 as MCMXC
     * 2014 as MMXIV
     * 2018 as MMXVIII
    StringBuilder romans = new StringBuilder();
    // Use LinkedHashMap to preserve entry order of HashMap *very important!*
    LinkedHashMap<Integer, String> romanMapping = new LinkedHashMap<Integer, String>();
    romanMapping.put(1000, "M");
    romanMapping.put(500, "D");
    romanMapping.put(100, "C");
    romanMapping.put(50, "L");
    romanMapping.put(10, "X");
    romanMapping.put(5, "V");
    romanMapping.put(1, "I");

    // Iterate through the LinkedHashMap to build our Roman numeral string
    for(Map.Entry<Integer, String> entry : romanMapping.entrySet()){
        // Get the number of Roman numeral letters we'll need to correspond to the current num slot value
        int curPowerCount = num / entry.getKey();
        for(int i = curPowerCount; i > 0; i--){
        // number only needs remaining value for next iteration, so modulate!
        num %= entry.getKey();
    return romans.toString();

- Mark Rich July 31, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

Since it is a design question, how about something like this.

interface Convertable {
	public function convert(int)
public class RomanNumerals implements Convertable {
        public function convert (int $) {
		// implementation to convert integer to RomanNumerals

If we go with this pattern then we could extend this design for any kind of other numerals/integer. Please let me know your feedback. Thanks.

- rotate2010 September 24, 2018 | Flag Reply

Add a Comment

Writing Code? Surround your code with {{{ and }}} to preserve whitespace.


is a comprehensive book on getting a job at a top tech company, while focuses on dev interviews and does this for PMs.

Learn More


CareerCup's interview videos give you a real-life look at technical interviews. In these unscripted videos, watch how other candidates handle tough questions and how the interviewer thinks about their performance.

Learn More

Resume Review

Most engineers make critical mistakes on their resumes -- we can fix your resume with our custom resume review service. And, we use fellow engineers as our resume reviewers, so you can be sure that we "get" what you're saying.

Learn More

Mock Interviews

Our Mock Interviews will be conducted "in character" just like a real interview, and can focus on whatever topics you want. All our interviewers have worked for Microsoft, Google or Amazon, you know you'll get a true-to-life experience.

Learn More