So I am studying for my Algorithm theory exam and this is the problem i could not solve:
Given numbers $x_1, x_2, ..., x_n$ which are the sizes of $n$ files and disk capacity $D$. Determine if you can seperate these files into $3$ disks so that, in every disk sum of doesn't exceed $D$. Justify that this problem belongs to class NP
So i am thinking you can seperate only if:
$x_i < D$ and if $x_1 + x_2 + ... + x_n > 3\cdot D$
Are these the only rules?