I guess because of this condition "The input array should not be modified!"

When debugging your code, print the input, otherwise, how would you know why your code fails?

"ngkoxnjgdidjvbb20r79gwfftpw0s5kbof9vvp8wr9eq50o6b48b8nmefj1nll6x2tzt29e2qc5dgjt5wik8hau1szunqztc5j4okdx851ty7ak2stlb29qdykixi6gqd7hcalm6048ncz5zmic646yendi76a0leihwjt8kfatvqr0zlr8t4ixiv64gnfrccikctesxq0xhqty9584x62pmkvcgsv50eerekh6nsj9xuulehpjcsa77s6yntds8pltsrryeu7jnv6v"

Object[]{"v", 2} // your code returns this 

If there are two or more characters with the same l return the first in order of appearance.

"bb" is clearly before than "vv" there. Now fix your code.

Please give examples of edge cases. Regards, suic