In the Colored Bin Packing problem a set of items with varying weights and colors must be packed into bins of uniform weight limit such that no two items of the same color may be packed adjacently within a bin. We solve this problem for the case where there are two or more colors when the items have zero weight and when the items have unit weight. Our algorithms are optimal and run in linear time. Since our algorithms apply for two or more colors, they demonstrate that the problem does not get harder as the number of colors increases. We also provide closed-form expressions for the optimal number of bins.
Dosa and Epstein @cite_5 extend the results from @cite_2 . They prove that online Colored Bin Packing with alternation for 3 or more colors is harder than the 2-color version. Furthermore, the authors show that 2-color algorithms do not apply to 3 or more color problems. Lastly, they present a 4-competitive algorithm for the problem. This is a modified version of the earlier Pseudo, appropriately named Balanced-Pseudo. Instead of randomly assigning items to available bins, Balanced-Pseudo assigns an item to the bin whose top color is the most frequent.
@cite_5 @cite_2
166203068 2177689085
We study a variant of online bin packing, called colorful bin packing. In this problem, items that are presented one by one are to be packed into bins of size 1. Each item i has a size s i ∈ [0,1] and a color (c_i C ), where ( C ) is a set of colors (that is not necessarily known in advance). The total size of items packed into a bin cannot exceed its size, thus an item i can always be packed into a new bin, but an item cannot be packed into a non-empty bin if the previous item packed into that bin has the same color, or if the occupied space in it is larger than 1 − s i . This problem generalizes standard online bin packing and online black and white bin packing (where (| C |=2 )). We prove that colorful bin packing is harder than black and white bin packing in the sense that an online algorithm for zero size items that packs the input into the smallest possible number of bins cannot exist for (| C | 3 ), while it is known that such an algorithm exists for (| C |=2 ). We show that natural generalizations of classic algorithms for bin packing fail to work for the case (| C | 3 ), and moreover, algorithms that perform well for black and white bin packing do not perform well either, already for the case (| C |=3 ). Our main results are a new algorithm for colorful bin packing that we design and analyze, whose absolute competitive ratio is 4, and a new lower bound of 2 on the asymptotic competitive ratio of any algorithm, that is valid even for black and white bin packing. We introduce the following version of bin packing. The items are of two types (black and white), and in each bin the item types must alternate. We mostly investigate the online scenario. We study the competitiveness of some classical algorithms (First Best Worst Next Fit, Harmonic) — they do not perform very well — and for all online algorithms we also prove the universal lower bound (1+ 1 2 .7213 ) which significantly exceeds the known upper bound 1.58889 on classical online bin packing. We also design an online algorithm which is 3-competitive in the absolute sense. A 2.5-approximation algorithm and an APTAS is also given for the offline version.