HDU 6074 Phone Call (LCA+并查集, 2017 Multi-Univ Training Contest 4)
ProblemTherearenhousesinBytetown,labeledby1,2,…,n.Ineachhouse,thereisapersonlivinghere.LittleQlivesinhouse1.Therearen−1bidirectionalstreetsconnectingthesehouses,formingatreestructure.Inthisproblem,S(u