设G=(V,E)是一个简单连通图,V和且分别为G的顶点榘和边集.研究了单圈图的Wiener指数,利用单圈图的Wiener指数的计算公式,刻划了具有次大Wiener指数的单圈图的特征.
Let G = (V, E) be a simple connected graph with vertex set V and edge set E. The Wiener index W(G) of G is the sum of distances between all pairs of vertices in G, i.e., W(G)= ∑dG(u,v){u,v}belong to G Where dG(u,v)is the distance between vertices u and v in G. In this paper, we study the Wiener indices of unicyclic graphs.Using a formulation for calculating the Wiener index of an unicyclic graph according its struction, we characterize the graphs the second largest Wiener indices among all the unicyclic graphs of order n.