Kidney exchange programs have been established in several countries to organize kidney exchanges between incompatible patient-donor pairs.The core of these programs are algorithms to solve kidney exchange problem, which can be modeled as finding a maximum weight packing of vertex-disjoint cycles with length at most some small constant L (typically 2 ≤ L ≤ 5) in a directed graph.In generally, the objective function is maximizing the number of possible kidney transplants.In this paper, we study the random methods for the kidney exchange pro...