Linkedin Interview Question Software Developers
Country: United States
What this will do is just go through each character in the string; adding each value to the result. If it is bigger than the previous character, it will subtract 2 * the previous result because you added it once already when you were looking at the previous result.
import java.util.HashMap;
import java.util.Map;
public class RomanNumber {
final static Map<Character, Integer> romanNumberMap = new HashMap<Character, Integer>() {
{
this.put('I', 1);
this.put('V', 5);
this.put('X', 10);
this.put('L', 50);
this.put('C', 100);
this.put('D', 500);
this.put('M', 1000);
}
};
public static void main(String...args) {
System.out.println("I=" + romanNumber("I"));
System.out.println("III=" + romanNumber("III"));
System.out.println("VI=" + romanNumber("VI"));
System.out.println("XVI=" + romanNumber("XVI"));
System.out.println("IV=" + romanNumber("IV"));
System.out.println("IX=" + romanNumber("IX"));
System.out.println("XIV=" + romanNumber("XIV"));
System.out.println("LXIV=" + romanNumber("LXIV"));
}
public static int romanNumber(String roman) {
int result = 0;
char[] romanChars = roman.toCharArray();
char prevChar = '\0';
for (Character c : romanChars) {
if (!romanNumberMap.containsKey(c)) {
throw new IllegalArgumentException("Not a valid roman number");
}
result += romanNumberMap.get(c);
if (prevChar != '\0' && romanNumberMap.get(prevChar) < romanNumberMap.get(c)) {
result -= romanNumberMap.get(prevChar) * 2;
}
prevChar = c;
}
return result;
}
}
public class RomanToArabicNumber {
private static final Map romanToArabic = new HashMap<Character, Integer>();
public static void main(String[] args) {
romanToArabic.put('I', 1);
romanToArabic.put('V', 5);
romanToArabic.put('X', 10);
romanToArabic.put('L', 50);
romanToArabic.put('C', 100);
romanToArabic.put('D', 500);
romanToArabic.put('M', 1000);
int arabicRepre = toArabic("LXXXVIII");
System.out.println("value is "+arabicRepre);
}
private static int toArabic(String romanNum){
int arabicNum = 0;
if(romanNum == null){
return arabicNum;
}
for(int i=romanNum.length()-1; i>=0 ;){
Character firstChar = romanNum.charAt(i);
int firstCharValue = (int) romanToArabic.get(firstChar);
if(i-1 >= 0){
Character secondChar = romanNum.charAt(i-1);
int secondCharValue = (int)romanToArabic.get(secondChar);
if(firstCharValue>secondCharValue){
arabicNum = arabicNum+firstCharValue-secondCharValue;
}
else{
arabicNum = arabicNum+firstCharValue+secondCharValue;
}
i=i-2;
}else{
arabicNum = arabicNum+firstCharValue;
i = i-1;
}
}
return arabicNum;
}
}
class converter :
def __init__(self):
self.romanLetterMap = dict()
self.romanLetterMap['I']= 1
self.romanLetterMap["V"] = 5
self.romanLetterMap["X"] = 10
self.romanLetterMap["L"] = 50
self.romanLetterMap["C"] = 100
self.romanLetterMap["D"] = 500
self.romanLetterMap["M"] = 1000
print(self.romanLetterMap)
def convertToRoman(self,roman):
if roman is None or len(roman) <= 0 :
return None
prev=None
result = 0
for i in range(len(roman)):
romanLetter = roman[i]
if romanLetter not in self.romanLetterMap:
print("invalid letter sequence")
break
result += self.romanLetterMap[romanLetter]
if prev is not None and self.romanLetterMap[prev] < self.romanLetterMap[romanLetter]:
result -= 2* self.romanLetterMap[prev]
prev = romanLetter
return result
c = converter()
print("IV = ", c.convertToRoman("IV"))
print("X = ", c.convertToRoman("X"))
print("IX = ", c.convertToRoman("IX"))
print("XI = ", c.convertToRoman("XI"))
print("XIV = ", c.convertToRoman("XIV"))
class converter :
def __init__(self):
self.romanLetterMap = dict()
self.romanLetterMap['I']= 1
self.romanLetterMap["V"] = 5
self.romanLetterMap["X"] = 10
self.romanLetterMap["L"] = 50
self.romanLetterMap["C"] = 100
self.romanLetterMap["D"] = 500
self.romanLetterMap["M"] = 1000
print(self.romanLetterMap)
def convertToRoman(self,roman):
if roman is None or len(roman) <= 0 :
return None
prev=None
result = 0
for i in range(len(roman)):
romanLetter = roman[i]
if romanLetter not in self.romanLetterMap:
print("invalid letter sequence")
break
result += self.romanLetterMap[romanLetter]
if prev is not None and self.romanLetterMap[prev] < self.romanLetterMap[romanLetter]:
result -= 2* self.romanLetterMap[prev]
prev = romanLetter
return result
c = converter()
print("IV = ", c.convertToRoman("IV"))
print("X = ", c.convertToRoman("X"))
print("IX = ", c.convertToRoman("IX"))
print("XI = ", c.convertToRoman("XI"))
print("XIV = ", c.convertToRoman("XIV"))
int romanToInt(string s) {
int num = 0;
for(int i = 0; i < s.length(); i++ )
{
switch(s[i])
{
case 'M':
num += 1000;
break;
case 'D':
num += 500;
break;
case 'C':
num += 100;
break;
case 'L':
num += 50;
break;
case 'X':
num += 10;
break;
case 'V':
num += 5;
break;
case 'I':
num += 1;
break;
}
if( i > 0)
{
switch(s[i-1])
{
case 'C':
if( s[i] == 'D' || s[i] == 'M')
num -=200;
break;
case 'X':
if( s[i] == 'C' || s[i] == 'L')
num -=20;
break;
case 'I':
if( s[i] != 'I')
num -=2;
break;
}
}
}
return num;
}
public class RomanNumber {
private static final Map<Character, Integer> romanNumberMap;
static {
Map<Character, Integer> initMap = new HashMap<Character, Integer>();
initMap.put('I', 1);
initMap.put('V', 5);
initMap.put('X', 10);
initMap.put('L', 50);
initMap.put('C', 100);
initMap.put('D', 500);
initMap.put('M', 1000);
romanNumberMap = Collections.unmodifiableMap(initMap);
}
public static void main(String[] args) {
System.out.println(romanNumber("MMCCCXLIX"));
}
private static int romanNumber(String string) {
char[] charArr = string.toCharArray();
int retVal = 0;
int prev = 0;
for (int i = 0; i < charArr.length; i++) {
if (i > 0)
prev = romanNumberMap.get(charArr[i - 1]);
retVal += romanNumberMap.get(charArr[i]);
if (romanNumberMap.get(charArr[i]) > prev) {
retVal -= prev * 2;
}
}
return retVal;
}
}
public class RomanNumber {
private static final Map<Character, Integer> romanNumberMap;
static {
Map<Character, Integer> initMap = new HashMap<Character, Integer>();
initMap.put('I', 1);
initMap.put('V', 5);
initMap.put('X', 10);
initMap.put('L', 50);
initMap.put('C', 100);
initMap.put('D', 500);
initMap.put('M', 1000);
romanNumberMap = Collections.unmodifiableMap(initMap);
}
public static void main(String[] args) {
System.out.println(romanNumber("MMCCCXLIX"));
}
private static int romanNumber(String string) {
char[] charArr = string.toCharArray();
int retVal = 0;
int prev = 0;
for (int i = 0; i < charArr.length; i++) {
if (i > 0)
prev = romanNumberMap.get(charArr[i - 1]);
retVal += romanNumberMap.get(charArr[i]);
if (romanNumberMap.get(charArr[i]) > prev) {
retVal -= prev * 2;
}
}
return retVal;
}
}
Strategy: Read string and add values to a stack.
Then pop the stack and increment result while remembering the max. value encountered.
If new value is smaller than max value encountered, substract.
def roman_to_int(roman):
valid_dict = dict((k,v) for k, v in zip('ivxcdm', [1, 5, 10, 100, 500, 1000]))
values = []
for char in roman.lower():
if char in valid_dict:
values.append(valid_dict[char])
else:
raise KeyError("Roman number is not valid.")
max_val = 0
result = 0
while values:
val = values.pop()
if val >= max_val:
max_val = val
result += val
elif val < max_val:
result -= val
return result
if __name__ == '__main__':
print roman_to_int('XCVI') # 96
print roman_to_int('XCIX') # 99
print roman_to_int('XXXV') # 35
int GetInteger(char digit)
{
if (digit == 'I')
return 1;
if (digit == 'V')
return 5;
if (digit == 'X')
return 10;
if (digit == 'L')
return 50;
if (digit == 'C')
return 100;
if (digit == 'D')
return 500;
if (digit == 'M')
return 1000;
return 0;
}
int RomanToInt(std::string roman)
{
int previousDigit = GetInteger(roman[roman.size() - 1]);
int result = previousDigit;
for(int i = roman.size() - 2; i >= 0; i--)
{
int currentDigit = GetInteger(roman[i]);
if (currentDigit < previousDigit)
{
result += currentDigit * -1;
}
else
{
result += currentDigit;
}
previousDigit = currentDigit;
}
return result;
}
int main()
{
std::string roman = "MCMLXXXVI";
std::cout<<RomanToInt(roman);
return 0;
}
import re
numerals = {"M": 1000, "CM": 900, "D": 500, "CD": 400, "C": 100,
"XC": 90, "L": 50, "XL": 40, "X": 10, "V": 5, "IV": 4, "I": 1}
r = re.compile('|'.join(sorted(numerals.keys(), key=len, reverse=True)))
def to_roman(n, s=''):
for num, val in numerals.items():
if n // val:
n -= val
s += num
return to_roman(n, s)
if not n:
return s
def to_int(s):
tokens = r.findall(s)
return sum(numerals[t] for t in tokens)
import re
numerals = {"M": 1000, "CM": 900, "D": 500, "CD": 400, "C": 100,
"XC": 90, "L": 50, "XL": 40, "X": 10, "V": 5, "IV": 4, "I": 1}
r = re.compile('|'.join(sorted(numerals.keys(), key=len, reverse=True)))
def to_roman(n, s=''):
for num, val in numerals.items():
if n // val:
n -= val
s += num
return to_roman(n, s)
if not n:
return s
def to_int(s):
tokens = r.findall(s)
return sum(numerals[t] for t in tokens)
Some facts must be given about roman numerals:
-There are 7 symbols I V X L C D M.
-Each symbol has the following respective integer values 1 5 10 50 100 500 1000.
-The symbols in a roman string are summed in a special way such that the string matches the value known.
Using the information above we can work out a few examples that show us how the value of a roman string is calculated.
Ex 1. LXXXVI =86 this can be expanded into the sum 1 + 5 +10 +10 + 10 + 50.
Ex 2. MDCC =1700 =100 + 100 + 500 + 1000.
Ex 3. IV =4 = 5 + (-1).
Strategy:
Starting from the last symbol of the roman string we add to the total.
Then we go to the next symbol to the left.
If the value of this symbol is smaller than the last symbol we looked at let us subtract it otherwise add it to the total.
Continue onto process symbols like this until we have processed the first symbol of the roman string.
Java Snippet:
int romanNumber(String roman){ int valueOfLastChar = 0, valueOfCurrentChar =0; int total = 0; for(int i= roman.length()-1; 0<=i; i--){ switch(roman.charAt(i)){ case 'I': valueOfCurrentChar = 1; break; case 'V': valueOfCurrentChar = 5; break; case 'X': valueOfCurrentChar = 10; break; case 'L': valueOfCurrentChar = 50; break; case 'C': valueOfCurrentChar = 100; break; case 'D': valueOfCurrentChar = 500; break; case 'M': valueOfCurrentChar = 1000; break; } total += (valueOfCurrentChar < valueOfLastChar) ? -1*valueOfCurrentChar : valueOfCurrentChar; valueOfLastChar = valueOfCurrentChar; } return total;}
- gfhd760 May 01, 2016