Maximum Colorful Cycles in Vertex-Colored Graphs

In this paper, we study the problem of finding a maximum colorful cycle a vertex-colored graph. Specifically, given a graph with colored vertices, the goal is to find a cycle containing the maximum number of colors. We aim to give a dichotomy overview on the complexity of the problem. We first show that the problem is NP-hard even for simple graphs such as split graphs, biconnected graphs, interval graphs. Then we provide polynomial-time algorithms for classes of vertex-colored threshold graphs and vertex-colored bipartite chain graphs, which are our main contributions.