BZOJ 1179: [Apio2009]Atm
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/* BZOJ 1179: [Apio2009]Atm Tarjan + 缩点 + 最长路 此题zhx在讲课时信誓旦旦的说递归tarjan过不了 他的做法是tarjan缩点 + dp最长路 可是我写了个缩点 + spfa最长路就过了... 然后一遍AC 2333.. */ #include <cstdio> #include <stack> #include <queue> #define Max 500900 inline int max (int a, int b) { return a > b ? a : b; } inline int min (int a, int b) { return a < b ? a : b; } void read (int &now) { now = 0; register char word = getchar (); while (word > ‘9‘ || word < ‘0‘) word = getchar (); while (word >= ‘0‘ && word <= ‘9‘) { now = now * 10 + word - ‘0‘; word = getchar (); } } struct Edge_Type { struct Edge { int to; int next; int dis; } edge[Max]; int Edge_Count; int edge_list[Max]; void Add_Edge (int from, int to) { Edge_Count++; edge[Edge_Count].to = to; edge[Edge_Count].next = edge_list[from]; edge_list[from] = Edge_Count; } }; Edge_Type Graph_1; Edge_Type Graph; int point_dis[Max]; int value[Max]; int N, M; struct Tarjan_Type { std :: stack <int> Stack; int number[Max]; int lowlink[Max]; int Scc_Count; int Count; int scc_number[Max]; void Tarjan_ (int N) { for (int i = 1; i <= N; i++) if (!number[i]) Dfs (i); } void Dfs (int now) { Count++; number[now] = Count; lowlink[now] = Count; Stack.push (now); for (int i = Graph_1.edge_list[now]; i; i = Graph_1.edge[i].next) if (!number[Graph_1.edge[i].to]) { Dfs (Graph_1.edge[i].to); lowlink[now] = min (lowlink[now], lowlink[Graph_1.edge[i].to]); } else if (!scc_number[Graph_1.edge[i].to]) lowlink[now] = min (lowlink[now], number[Graph_1.edge[i].to]); if (lowlink[now] == number[now]) { Scc_Count++; int res = now + 1; while (res != now) { res = Stack.top (); Stack.pop (); scc_number[res] = Scc_Count; point_dis[Scc_Count] += value[res]; } } } void Narrow_Point () { for (int now = 1; now <= N; now++) for (int i = Graph_1.edge_list[now]; i; i = Graph_1.edge[i].next) if (scc_number[now] != scc_number[Graph_1.edge[i].to]) Graph.Add_Edge (scc_number[now], scc_number[Graph_1.edge[i].to]); } }; Tarjan_Type Make; struct Spfa_Type { int distance[Max]; std :: queue <int> Queue; bool visit[Max]; int S; void Do_Spfa (int S) { Queue.push (S); visit[S] = true; int now; distance[S] = point_dis[S]; while (!Queue.empty ()) { now = Queue.front (); Queue.pop (); visit[now] = false; for (int i = Graph.edge_list[now]; i; i = Graph.edge[i].next) if (distance[Graph.edge[i].to] < distance[now] + point_dis[Graph.edge[i].to]) { distance[Graph.edge[i].to] = distance[now] + point_dis[Graph.edge[i].to]; if (!visit[Graph.edge[i].to]) { Queue.push (Graph.edge[i].to); visit[Graph.edge[i].to] = true; } } } } }; Spfa_Type Spfa; int S, P; int main (int argc, char *argv[]) { read (N); read (M); int x, y; for (int i = 1; i <= M; i++) { read (x); read (y); Graph_1.Add_Edge (x, y); } for (int i = 1; i <= N; i++) read (value[i]); Make.Tarjan_ (N); Make.Narrow_Point (); read (S); read (P); Spfa.Do_Spfa (Make.scc_number[S]); int Answer = 0; for (int i = 1; i <= P; i++) { read (x); Answer = max (Answer, Spfa.distance[Make.scc_number[x]]); } printf ("%d", Answer); return 0; }
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缩点+spfa最长路bzoj 1179: [Apio2009]Atm