LC#13 brute-force approach to convert Roman string to Integer value

Author: NirmalSilwal

Leetcode/MustDoEasyList/RomanToInteger13.java

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+package MustDoEasyList;
+
+import java.util.HashMap;
+
+public class RomanToInteger13 {
+
+	public static int romanToInt(String s) {
+
+		HashMap<String, Integer> map = new HashMap<>();
+		initializeMap(map);
+
+		int len = s.length();
+		int idx = 0;
+		int sum = 0;
+		char ch1, ch2;
+		// parse string
+		while (idx < len) {
+			ch1 = ' ';
+			ch2 = ' ';
+
+			ch1 = s.charAt(idx);
+
+			if ((idx + 1) < len)
+				ch2 = s.charAt(idx + 1);
+
+			if (ch2 != ' ' && map.get("" + ch1) < map.get("" + ch2)) {
+				// if first character is small than next char
+				String currCombination = "" + ch1 + ch2;
+				sum += map.get(currCombination);
+				idx += 2; // two characters are combined so +2 in index
+
+			} else {
+				// considering only one Roman character
+				sum += map.get("" + ch1);
+				idx++;
+			}
+		}
+
+		return sum;
+	}
+
+	private static void initializeMap(HashMap<String, Integer> map) {
+
+		map.put("I", 1);
+		map.put("V", 5);
+		map.put("X", 10);
+		map.put("L", 50);
+		map.put("C", 100);
+		map.put("D", 500);
+		map.put("M", 1000);
+		// special cases
+		map.put("IV", 4);
+		map.put("IX", 9);
+		map.put("XL", 40);
+		map.put("XC", 90);
+		map.put("CD", 400);
+		map.put("CM", 900);
+	}
+
+	public static void main(String[] args) {
+		System.out.println(romanToInt("III"));
+		System.out.println(romanToInt("IV"));
+		System.out.println(romanToInt("IX"));
+		System.out.println(romanToInt("LVIII"));
+		System.out.println(romanToInt("MCMXCIV"));
+		System.out.println(romanToInt("MDCXCV"));
+
+		/*
+		 * testing character concatenation
+		 * 
+		 * System.out.println("" + 'c' + 'd');
+		 */
+	}
+}