update

src/main/java/rocks/zipcode/io/quiz4/fundamentals/StringEvaluator.java

 package rocks.zipcode.io.quiz4.fundamentals;
 
+import java.util.ArrayList;
+
 /**
  * @author leon on 11/12/2018.
  */
     }
 
     public static String[] getAllPrefixes(String string) {
-        int arrayLength = factorial(string.length()-1);
-        String[] prefixes = new String[arrayLength];
+        ArrayList<String> prefixes = new ArrayList<>();
         if(string.length()==1){
-            prefixes[0] = string;
+            prefixes.add(string);
+            String[] arr = new String[prefixes.size()];
+            arr = prefixes.toArray(arr);
+            return arr;
         }
         for(int i =0; i<string.length(); i++){
-            for(int j = 0; j<string.length(); j++){
-                if(i<j) {
-                    prefixes[i + j] = string.substring(i, j);
-                }
+            for(int j = string.length(); j>i; j--){
+                    prefixes.add(string.substring(i, j));
             }
         }
-        return prefixes;
+        String[] arr = new String[prefixes.size()];
+        arr = prefixes.toArray(arr);
+        return arr;
     }
 
     public static String[] getCommonPrefixes(String string1, String string2) {