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Add Roman To Integer conversion #720

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Merged
merged 2 commits into from
Mar 19, 2019
Merged

Add Roman To Integer conversion #720

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c14af04
Add Roman To Integer conversion
pandeyarun709 Mar 18, 2019
971d5f7
Format code in RomanToInteger.java
yanglbme Mar 19, 2019
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56 changes: 56 additions & 0 deletions Conversions/RomanToInteger.java
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Original file line number Diff line number Diff line change
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import java.util.*;

public class RomanToInteger {

private static Map<Character, Integer> map = new HashMap<>() {{
put('I', 1);
put('V', 5);
put('X', 10);
put('L', 50);
put('C', 100);
put('D', 500);
put('M', 1000);
}};

/**
* This function convert Roman number into Integer
*
* @param A Roman number string
* @return integer
*/
public static int romanToInt(String A) {

char prev = ' ';

int sum = 0;

int newPrev = 0;
for (int i = A.length() - 1; i >= 0; i--) {
char c = A.charAt(i);

if (prev != ' ') {
// checking current Number greater then previous or not
newPrev = map.get(prev) > newPrev ? map.get(prev) : newPrev;
}

int currentNum = map.get(c);

// if current number greater then prev max previous then add
if (currentNum >= newPrev) {
sum += currentNum;
} else {
// subtract upcoming number until upcoming number not greater then prev max
sum -= currentNum;
}

prev = c;
}

return sum;
}

public static void main(String[] args) {
int sum = romanToInt("MDCCCIV");
System.out.println(sum);
}
}