This is definitely the best solution I've seen for finding the unknown out of several possible ones.

Almost. If itemCount could be zero, then that fails. Use

return (itemCount + itemsPerPage - 1) % ItemsPerPage + 1;

I don't remember if zero is allowed in the statement, but it should just be a habit in Java, C and C++ to avoid negative arguments to %.

Liked your way of mixing characters with ints.

duplicate issue below

A plus sign before (possibly negative) rand.nextInt() doesn't make it positive. At least not in Java.

Thanks, sorry for the delay.

Thank you.

Perfect. Not used any Math.pow() and the number of divisions is minimized

Input: ORD, K^G, Q^E, DAD, T^B, A^L, B<F, S^I, AKA, AIA, JMJ, PFG, MGM

Output:BEAHJFOKLTS

It's not even of length 20.

Hi! Thanks for your feedback! Actualy I'm not really surprised. I spent a lot of effort on this kata. But every time there was an edge case which ruined my another attempt. May be the test cases should be improved to invalidate solutions such as mine.

Hi. Unfortunately, your solution is incomplete. Consider this input:

{88, 90, 89, 87}.

Your program cannot find a solution, while it exists, e.g.:

{88, 78, 77, 76, 86, 96, 95, 94, 93, 92, 91, 90, 80, 81, 82, 83, 84, 85, 75, 65, 66, 67, 68, 69, 79, 89, 99, 98, 97, 87}.

Moreover, on this input:

{88, 91, 89, 83}

it returns a path of length 34:

{88, 87, 86, 85, 84, 74, 73, 72, 71, 81, 91, 90, 80, 70, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 79, 89, 99, 98, 97, 96, 95, 94, 93, 83},

while there is a path of length 32:

{88, 78, 77, 76, 75, 74, 73, 72, 82, 92, 91, 81, 71, 61, 62, 63, 64, 65, 66, 67, 68, 69, 79, 89, 99, 98, 97, 87, 86, 85, 84, 83}.

Hi. Unfortunately, your solution is incomplete. Consider this input:

{30, 1, 28, 0}.

Your program cannot find a solution, while it exists, e.g.:

{30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 29, 19, 9, 8, 7, 6, 5, 4, 3, 2, 1, 11, 12, 13, 14, 15, 16, 17, 18, 28, 27, 26, 25, 24, 23, 22, 21, 20, 10, 0}.

Moreover, on this input:

{56, 30, 21, 41}

it returns a path of length 15:

{56, 55, 54, 53, 52, 51, 50, 40, 30, 31, 21, 22, 32, 42, 41},

while there is a path of length 13:

{56, 55, 54, 53, 52, 51, 50, 40, 30, 20, 21, 31, 41}.

Hi. Unfortunately, your solution is incomplete. Consider this input:

{88, 29, 98, 58}.

Your program cannot find a solution, while it exists, e.g.:

{88, 78, 68, 67, 57, 47, 48, 49, 39, 29, 28, 38, 37, 36, 46, 56, 66, 76, 77, 87, 97, 98, 99, 89, 79, 69, 59, 58}.

Moreover, on this input:

{4, 19, 21, 6}

it returns a path of length 39:

{4, 3, 13, 12, 11, 10, 20, 30, 40, 41, 42, 43, 44, 45, 46, 36, 37, 27, 28, 29, 19, 18, 17, 16, 26, 25, 35, 34, 33, 32, 31, 21, 22, 23, 24, 14, 15, 5, 6},

while there is a path of length 35:

{4, 3, 2, 1, 0, 10, 20, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 29, 19, 18, 28, 27, 26, 25, 24, 23, 22, 21, 11, 12, 13, 14, 15, 5, 6}.

Hi. Unfortunately, your solution is incomplete. Consider this input:

{0, 2, 13, 1}.

Your program cannot find a solution, while it exists, e.g.:

{0, 10, 20, 30, 31, 32, 33, 34, 24, 14, 4, 3, 2, 12, 13, 23, 22, 21, 11, 1}.

Moreover, on this input:

{53, 49, 38, 69}

it returns a path of length 26:

{53, 43, 44, 45, 46, 47, 48, 49, 39, 38, 37, 36, 35, 34, 33, 32, 42, 52, 62, 63, 64, 65, 66, 67, 68, 69},

while there is a path of length 20:

{53, 43, 33, 23, 24, 25, 26, 27, 28, 29, 39, 49, 48, 38, 37, 47, 57, 67, 68, 69}.