The descrition mentions arrays of at least 4 numbers, in reality arrays of length 0 and 1 are passed.
this is evident by the out of bound erros when accessing the elements.

the description should be updated

All test pass but Test4 in JAva.
I tried to cast to int, round, floor and ceil the division when I calculate the mean.
What values are in test4?
I cannot find why it is failing!

I think that it should be clearly stated that an empty string should return true.
If x is not present it cannot be followed by y, there fore is cannot be true