Amazon Interview Question for Software Engineer / Developers


Country: United States
Interview Type: In-Person




Comment hidden because of low score. Click to expand.
1
of 1 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.
0
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.
0
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.
0
of 0 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){
                    result.append(roman[index]);
                    count--;
                }
                x = x % numbers[index];
            }
            index++;
        }
        
        return result.toString();
    }

- AJ June 24, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
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.
0
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--){
            romans.append(entry.getValue());
        }
        // number only needs remaining value for next iteration, so modulate!
        num %= entry.getKey();
    }
    
    return romans.toString();
}

- Mark Rich July 31, 2018 | Flag Reply


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