http://www.lydsy.com/JudgeOnline/problem.php?id=3993
裸题。
二分后强行网络流。
#include<cstdio> #include<cstdlib> #include<iostream> #include<fstream> #include<algorithm> #include<cstring> #include<string> #include<cmath> #include<queue> #include<stack> #include<map> #include<utility> #include<set> #include<bitset> #include<vector> #include<functional> #include<deque> #include<cctype> #include<climits> #include<complex> //#include<bits/stdc++.h>适用于CF,UOJ，但不适用于poj using namespace std; typedef long long LL; typedef double DB; typedef pair<int,int> PII; typedef complex<DB> CP; #define mmst(a,v) memset(a,v,sizeof(a)) #define mmcy(a,b) memcpy(a,b,sizeof(a)) #define fill(a,l,r,v) fill(a+l,a+r+1,v) #define re(i,a,b) for(i=(a);i<=(b);i++) #define red(i,a,b) for(i=(a);i>=(b);i--) #define ire(i,x) for(typedef(x.begin()) i=x.begin();i!=x.end();i++) #define fi first #define se second #define m_p(a,b) make_pair(a,b) #define p_b(a) push_back(a) #define SF scanf #define PF printf #define two(k) (1<<(k)) template<class T>inline T sqr(T x){return x*x;} template<class T>inline void upmin(T &t,T tmp){if(t>tmp)t=tmp;} template<class T>inline void upmax(T &t,T tmp){if(t<tmp)t=tmp;} inline int sgn(DB x){if(abs(x)<1e-5)return 0;return(x>0)?1:-1;} const DB Pi=acos(-1.0); int gint() { int res=0;bool neg=0;char z; for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar()); if(z==EOF)return 0; if(z=='-'){neg=1;z=getchar();} for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar()); return (neg)?-res:res; } LL gll() { LL res=0;bool neg=0;char z; for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar()); if(z==EOF)return 0; if(z=='-'){neg=1;z=getchar();} for(;z!=EOF && isdigit(z);res=res*10+z-'0',z=getchar()); return (neg)?-res:res; } const int maxn=50; const DB INF=1e50; int n,m; int a[maxn+10],b[maxn+10]; int mp[maxn+10][maxn+10]; DB sum; int S,T,now,info[maxn+maxn+10],last[maxn+maxn+10]; struct Tedge{int v,next;DB flow;}edge[2*(maxn+maxn+maxn*maxn)+10000]; void addedge(int u,int v,DB flow) { now++;edge[now].v=v;edge[now].next=info[u];edge[now].flow=flow;info[u]=now; now++;edge[now].v=u;edge[now].next=info[v];edge[now].flow=0;info[v]=now; } void build(DB mid) { int i,j; now=-1;mmst(info,-1); S=0;T=m+n+1; re(i,1,m)addedge(S,i,mid*DB(b[i])); re(i,1,n)addedge(m+i,T,DB(a[i])); re(i,1,m)re(j,1,n)if(mp[i][j])addedge(i,m+j,INF); } int level[maxn+maxn+10]; int head,tail,que[maxn+maxn+10]; int Dinic_build() { int i; re(i,0,n+m+1)level[i]=0; level[que[head=tail=1]=S]=1; while(head<=tail) { int u=que[head++],v;DB flow; for(i=info[u],v=edge[i].v,flow=edge[i].flow;i!=-1;i=edge[i].next,v=edge[i].v,flow=edge[i].flow) if(!level[v] && sgn(flow)>0) level[que[++tail]=v]=level[u]+1; } return level[T]; } DB Dinic(int u,DB delta) { if(u==T)return delta; int &i=last[u],v;DB res=0.0,flow; for(v=edge[i].v,flow=edge[i].flow;i!=-1;i=edge[i].next,v=edge[i].v,flow=edge[i].flow) if(level[u]+1==level[v] && sgn(flow)>0) { DB tmp=Dinic(v,min(flow,delta)); delta-=tmp; res+=tmp; edge[i].flow-=tmp; edge[i^1].flow+=tmp; if(sgn(delta)<=0)return res; } return res; } int check(DB mid) { build(mid); int i;DB maxflow=0.0; while(Dinic_build()) { re(i,0,m+n+1)last[i]=info[i]; maxflow+=Dinic(S,INF); } return sgn(maxflow-sum)>=0; } int main() { freopen("war.in","r",stdin); freopen("war.out","w",stdout); int i,j; n=gint();m=gint(); re(i,1,n)a[i]=gint(); re(i,1,m)b[i]=gint(); re(i,1,m)re(j,1,n)mp[i][j]=gint(); re(i,1,n)sum+=DB(a[i]); int tmp=check(10.0); DB l=0.0,r=10000000.0; while(l+1e-5<r) { DB mid=(l+r)/2.0; if(check(mid)) r=mid; else l=mid; } DB ans=(l+r)/2.0; if(sgn(ans)==0)ans=0.0; PF("%0.6lf ",ans); return 0; }