67 lines
1.4 KiB
Java
67 lines
1.4 KiB
Java
package Conversions;
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import java.util.*;
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public class RomanToInteger {
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private static Map<Character, Integer> map =
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new HashMap<Character, Integer>() {
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/** */
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private static final long serialVersionUID = 87605733047260530L;
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{
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put('I', 1);
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put('V', 5);
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put('X', 10);
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put('L', 50);
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put('C', 100);
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put('D', 500);
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put('M', 1000);
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}
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};
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// Roman Number = Roman Numerals
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/**
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* This function convert Roman number into Integer
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*
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* @param A Roman number string
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* @return integer
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*/
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public static int romanToInt(String A) {
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A = A.toUpperCase();
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char prev = ' ';
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int sum = 0;
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int newPrev = 0;
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for (int i = A.length() - 1; i >= 0; i--) {
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char c = A.charAt(i);
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if (prev != ' ') {
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// checking current Number greater then previous or not
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newPrev = map.get(prev) > newPrev ? map.get(prev) : newPrev;
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}
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int currentNum = map.get(c);
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// if current number greater then prev max previous then add
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if (currentNum >= newPrev) {
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sum += currentNum;
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} else {
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// subtract upcoming number until upcoming number not greater then prev max
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sum -= currentNum;
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}
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prev = c;
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}
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return sum;
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}
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public static void main(String[] args) {
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int sum = romanToInt("MDCCCIV");
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System.out.println(sum);
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}
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}
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