tasks a-s

Task/Roman-numerals-Decode/Java/roman-numerals-decode.java

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+public class Roman {
+	private static int decodeSingle(char letter) {
+		switch(letter) {
+			case 'M': return 1000;
+			case 'D': return 500;
+			case 'C': return 100;
+			case 'L': return 50;
+			case 'X': return 10;
+			case 'V': return 5;
+			case 'I': return 1;
+			default: return 0;
+		}
+	}
+	public static int decode(String roman) {
+		int result = 0;
+		String uRoman = roman.toUpperCase(); //case-insensitive
+		for(int i = 0;i < uRoman.length() - 1;i++) {//loop over all but the last character
+			//if this character has a lower value than the next character
+			if (decodeSingle(uRoman.charAt(i)) < decodeSingle(uRoman.charAt(i+1))) {
+				//subtract it
+				result -= decodeSingle(uRoman.charAt(i));
+			} else {
+				//add it
+				result += decodeSingle(uRoman.charAt(i));
+			}
+		}
+		//decode the last character, which is always added
+		result += decodeSingle(uRoman.charAt(uRoman.length()-1));
+		return result;
+	}
+	
+	public static void main(String[] args) {
+		System.out.println(decode("MCMXC")); //1990
+		System.out.println(decode("MMVIII")); //2008
+		System.out.println(decode("MDCLXVI")); //1666
+	}
+}