final changes

src/main/java/rocks/zipcode/quiz5/fundamentals/StringUtils.java

@@ -73,17 +73,18 @@ public class StringUtils {
 
         StringBuilder builder = new StringBuilder();
 
+        char previous = 'k';
+        int counter = 0;
+
         char arr[] = str.toCharArray();
 
         for(int i = 0; i < arr.length; i++){
-                if(arr[i] != arr[j]){
-                    builder.append(arr[i]);
+                if(previous != arr[i]){
+                    arr[counter++] = arr[i];
+                    previous = arr[i];
                 }
             }
-
-
-
-        return builder.toString();
+        return new String(arr).substring(0,counter);
     }
 
     public static String invertCasing(String str) {