🤖 AI Summary
This study addresses the generalized coupon collector problem, which involves computing statistical quantities—such as the expectation, variance, and second moment—of the number of draws required to collect a specified number of coupons of certain types under arbitrary drawing probabilities. The work proposes the first polynomial-time algorithm applicable to any probability distribution over coupon types, establishing a unified framework that accommodates both targeted subsets and multi-copy collection requirements. By leveraging a tailored Markov model combined with dynamic programming, the method efficiently traverses the high-dimensional state space to enable exact computation of these moments. Under the uniform distribution, the algorithm achieves polynomial time complexity in the number of coupon types $n$, substantially enhancing computational feasibility compared to prior approaches.
📝 Abstract
The Coupon Collector Problem (CCP) is a well-known combinatorial problem that seeks to estimate the number of random draws required to complete a collection of $n$ distinct coupon types. Various generalizations of this problem have been applied in numerous engineering domains. However, practical applications are often hindered by the computational challenges associated with deriving numerical results for moments and distributions. In this work, we present three algorithms for solving the most general form of the CCP, where coupons are collected under any arbitrary drawing probability, with the objective of obtaining $t$ copies of a subset of $k$ coupons from a total of $n$. The First algorithm provides the base model to compute the expectation, variance, and the second moment of the collection process. The second algorithm utilizes the construction of the base model and computes the same values in polynomial time with respect to $n$ under the uniform drawing distribution, and the third algorithm extends to any general drawing distribution. All algorithms leverage Markov models specifically designed to address computational challenges, ensuring exact computation of the expectation and variance of the collection process. Their implementation uses a dynamic programming approach that follows from the Markov models framework, and their time complexity is analyzed accordingly.