solves roman to int

Author: anishLearnsToCode

README.md

@@ -5,8 +5,8 @@
 |:--------:|------|:----------:|:--------:|
 | 1 | [Two Sum](https://leetcode.com/problems/two-sum/) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/TwoSum.java) | 
 | 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/ReverseInteger.java) |
-| 9 | [PalindromeNumber](https://leetcode.com/problems/palindrome-number/) | Easy | |
-| 2 | []() | Easy | |
+| 9 | [PalindromeNumber](https://leetcode.com/problems/palindrome-number/) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/PalindromeNumber.java) |
+| 2 | [Roman To Integer](https://leetcode.com/problems/roman-to-integer/) | Easy | |
 | 2 | []() | Easy | |
 | 2 | []() | Easy | |
 | 2 | []() | Easy | |

src/RomanToInteger.java

@@ -0,0 +1,41 @@
+// https://leetcode.com/problems/roman-to-integer/
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Scanner;
+
+public class RomanToInteger {
+    private static final Map<Character, Integer> romanNumerals = new HashMap<>();
+
+    static {
+        romanNumerals.put('I', 1);
+        romanNumerals.put('V', 5);
+        romanNumerals.put('X', 10);
+        romanNumerals.put('L', 50);
+        romanNumerals.put('C', 100);
+        romanNumerals.put('D', 500);
+        romanNumerals.put('M', 1000);
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        String roman = scanner.next();
+        System.out.println(romanToInt(roman));
+    }
+
+    private static int romanToInt(String string) {
+        int value = 0;
+        for (int index = 0 ; index < string.length() ; index++) {
+            if (index < string.length() - 1 && value(string.charAt(index)) < value(string.charAt(index + 1))) {
+                value -= value(string.charAt(index));
+            } else {
+                value += value(string.charAt(index));
+            }
+        }
+        return value;
+    }
+
+    private static int value(char character) {
+        return romanNumerals.get(character);
+    }
+}