mystery8 methods
public static int[] duplicateAll(int[] arr)
{
int[] newArr = new int[arr.length * 2];
duplicateAll(arr, newArr, 0);
return newArr;
}
private static void duplicateAll(int[] oldArr, int[] newArr, int oldIndex)
{
if(oldIndex >= oldArr.length)
return;
newArr[oldIndex] = oldArr[oldIndex];
newArr[oldArr.length + oldIndex] = oldArr[oldIndex];
duplicateAll(oldArr, newArr, oldIndex + 1);
}
The method returns a new array in which the element in the old array appear twice.
duplicateAll(new int[]{1, 2, 3, 4}) returns [1, 2, 3, 4, 1, 2, 3, 4]