added file

Author: Mohsin Khan

String/Greedy Algorithm/Roman to Integer.java

@@ -0,0 +1,36 @@
+class Solution {
+    public int romanToInt(String s) {
+        int ans = 0, num = 0;
+        for (int i = s.length() - 1; i >=0; i--) {
+            switch (s.charAt(i)) {
+                case 'I':
+                    num = 1;
+                    break;
+                case 'V':
+                    num = 5;
+                    break;
+                case 'X':
+                    num = 10;
+                    break;
+                case 'L':
+                    num = 50;
+                    break;
+                case 'C':
+                    num = 100;
+                    break;
+                case 'D':
+                    num = 500;
+                    break;
+                case 'M':
+                    num = 1000;
+                    break;
+            }
+            if (4 * num < ans)
+                ans -= num;
+            else
+                ans += num;
+        }
+        return ans;
+
+    }
+}