package kyu6;

/**

* 6 kyu - Tribonacci Sequence

*

* https://www.codewars.com/kata/556deca17c58da83c00002db/java

*

* DESCRIPTION:

* Well met with Fibonacci bigger brother, AKA Tribonacci.

*

* As the name may already reveal, it works basically like a Fibonacci, but summing the last 3 (instead of 2) numbers of the sequence to generate the next.

* And, worse part of it, regrettably I won't get to hear non-native Italian speakers trying to pronounce it :(

*

* Well, you may have guessed it by now, but to be clear: you need to create a fibonacci function that given a signature array/list, returns the first n elements - signature included of the so seeded sequence.

*

* Signature will always contain 3 numbers; n will always be a non-negative number; if n == 0, then return an empty array (except in C return NULL) and be ready for anything else which is not clearly specified ;)

*/

public class Xbonacci {

public double[] tribonacci(double[] s, int n) {

double[] arr = new double[n];

if (n == 0) return arr;

arr[0] = s[0];

if (arr.length > 1)arr[1] = s[1];

if (arr.length > 2)arr[2] = s[2];

for (int i = 3; i < arr.length; i++) {

arr[i] = arr[i-1] + arr[i-2] + arr[i-3];

}

return arr;

}

}