JavaAlgorithms/Conversions/RomanToInteger.java
yanglbme 971d5f75e9
Format code in RomanToInteger.java
* Format code
* Remove redundant code
2019-03-19 08:40:02 +08:00

57 lines
1.3 KiB
Java

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);
}
}