【XIV Open Cup E.V. Pankratiev. GP of SPb. H】Reachability 题解
题目大意 一幅有向图有nnn个结点,初始没有边。 有qqq个操作,四种类型:+ovka1⋯ak+~o~v~k~a_1~\cdots~a_k+ovka1⋯ak:加入边(v,a1),⋯ ,(v,ak)(v,a_1),\cdots,(v,a_k)(v,a1),⋯,(v,ak)+ivka1⋯ak+~i~v~k~a_1~\cdots~a_k+ivka1⋯ak:加入边(a1,v),⋯ ,(ak,v)(a_