二次联通门 : BZOJ 4819: [Sdoi2017]新生舞会
/*BZOJ 4819: [Sdoi2017]新生舞会二分 + 01分数规划 + 最小费用流二分出一个答案费用流检验*/ #include <cstdio> #include <iostream> #include <queue> #include <cstring>const int BUF = 12312312; char Buf[BUF], *buf = Buf;#define Max 205 inline void read (int &now) {for (now = 0; !isdigit (*buf); ++ buf);for (; isdigit (*buf); now = now * 10 + *buf - '0', ++ buf); } using std :: min; using std :: max;#define INF 1e8 struct E {E *n, *r;int to, f;double c; };class Net_Flow {private :E poor[Max * Max * 2], *list[Max], *Tail, *pre[Max]; int S, T, can[Max];double deep[Max];bool visit[Max];public :inline void In (int u, int v, int f, double c){++ Tail, Tail->to = v, Tail->n = list[u], list[u] = Tail;Tail->c = c, Tail->f = f;++ Tail, Tail->to = u, Tail->n = list[v], list[v] = Tail;Tail->c = -c, Tail->f = 0;(Tail - 1)->r = Tail, Tail->r = (Tail - 1);} inline void Set_ST (int x, int y) { S = x, T = y; }bool Bfs (){std :: queue <int> Queue; Queue.push (S); can[S] = INF;for (register int i = 0; i < Max; ++ i) deep[i] = -INF;memset (visit, false, sizeof visit); E *e; int now;for (deep[S] = 0, visit[S] = true; !Queue.empty (); Queue.pop ()){now = Queue.front (); visit[now] = false;for (e = list[now]; e; e = e->n)if (e->f && deep[e->to] < deep[now] + e->c){pre[e->to] = e, can[e->to] = min (can[now], e->f);deep[e->to] = deep[now] + e->c;if (!visit[e->to])visit[e->to] = true, Queue.push (e->to);}}return deep[T] > -INF;}double Dinic (){double res = 0;for (int x; Bfs (); ){x = can[T];for (int t = T; t != S; t = pre[t]->r->to)pre[t]->f -= x, pre[t]->r->f += x;res += deep[T]; }return res;}void Clear (){Tail = poor;for (register int i = 0; i < Max; ++ i)list[i] = NULL;} }; Net_Flow Flow;double a[Max][Max], b[Max][Max];int Main () {fread (buf, 1, BUF, stdin);int N, x; read (N); register int i, j;for (i = 1; i <= N; ++ i)for (j = 1; j <= N; ++ j)read (x), a[i][j] = (double) x;for (i = 1; i <= N; ++ i)for (j = 1; j <= N; ++ j)read (x), b[i][j] = (double) x;int S, T; Flow.Set_ST (S = 0, T = (N << 1) + 1);double l, r = 1e4, Mid, res;for (int Time = 1; Time <= 37; ++ Time){Mid = (l + r) / 2.0; Flow.Clear ();for (i = 1; i <= N; ++ i)Flow.In (S, i, 1, 0), Flow.In (N + i, T, 1, 0);for (i = 1; i <= N; ++ i)for (j = 1; j <= N; ++ j)Flow.In (i, N + j, 1, a[i][j] - b[i][j] * Mid);res = Flow.Dinic ();if (res <= 0) r = Mid;else l = Mid;}printf ("%.6lf", l);return 0; } int ZlycerQan = Main (); int main (int argc, char *argv[]) {;}
