fix: removeDuplicates()

Exercise_19/Exercise_19_03/Exercise_19_03.java

@@ -9,14 +9,21 @@
 
 public class Exercise_19_03 {
 	/** Removes duplicate elements from an array list */
-	public static <E extends Comparable<E>> 
-			ArrayList<E> removeDuplicates(ArrayList<E> list) {
-		for (int i = 0; i < list.size() - 1; i++) {
-			for (int j = i + 1; j < list.size(); j++) {
-				if (list.get(i).compareTo(list.get(j)) == 0)
-					list.remove(j);
-			}
+	public static <E> ArrayList<E> removeDuplicates(ArrayList<E> list) {
+		ArrayList<E> new_list = new ArrayList<>();
+		for (int i = 0; i < list.size(); i++) {
+		    E o = list.get(i);
+		    if (notContains(o, new_list))
+			new_list.add(o);
 		}
-		return list;
-	} 
-}
+		return new_list;
+	}
+
+	public static <E> Boolean notContains(E o, ArrayList<E> list) {
+		for (int i = 0; i < list.size(); i++) {
+		    if (list.get(i).equals(o))
+			return false;
+		}
+		return true;
+	}
+}