【费用流】bzoj3280 小R的烦恼

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
#define MAXN 161
#define MAXM 40001
#define INF 2147483647
int S,T,Hos;
int N,M,K,sum;
int en,u[MAXM],v[MAXM],first[MAXN],next[MAXM],cap[MAXM],cost[MAXM];//Next Array
bool inq[MAXN];
int d[MAXN]/*spfa*/,p[MAXN]/*spfa*/,a[MAXN]/*可改进量*/;
queue<int>q;
void Init_MCMF()
{
memset(p,0,sizeof(p));
memset(a,0,sizeof(a));
memset(first,-1,sizeof(first));
memset(next,0,sizeof(next));
memset(u,0,sizeof(u));
memset(v,0,sizeof(v));
memset(cap,0,sizeof(cap));
memset(cost,0,sizeof(cost));
en=0;S=0;T=(N<<1)+M+2;Hos=T-1;sum=0;
}
void AddEdge(const int &U,const int &V,const int &W,const int &C)
{u[en]=U; v[en]=V; cap[en]=W; cost[en]=C; next[en]=first[U]; first[U]=en++;
u[en]=V; v[en]=U; cost[en]=-C; next[en]=first[V]; first[V]=en++;}
bool Spfa(int &Flow,int &Cost)
{
memset(d,0x7f,sizeof(d));
memset(inq,0,sizeof(inq));
d[S]=0; inq[S]=1; p[S]=0; a[S]=INF; q.push(S);
while(!q.empty())
{
int U=q.front(); q.pop(); inq[U]=0;
for(int i=first[U];i!=-1;i=next[i])
if(cap[i] && d[v[i]]>d[U]+cost[i])
{
d[v[i]]=d[U]+cost[i];
p[v[i]]=i;
a[v[i]]=min(a[U],cap[i]);
if(!inq[v[i]]) {q.push(v[i]); inq[v[i]]=1;}
}
}
if(d[T]>2100000000) return 0;
Flow+=a[T]; Cost+=d[T]*a[T]; int U=T;
while(U!=S)
{
cap[p[U]]-=a[T]; cap[p[U]^1]+=a[T];
U=u[p[U]];
}
return 1;
}
int Mincost()
{
int Flow=0,Cost=0;
while(Spfa(Flow,Cost));
if(Flow<sum) puts("impossible");
else printf("%d\n",Cost);
}
int A[51],B,C,D[51],E[51],zu;
int main()
{
scanf("%d",&zu);
for(int Z=1;Z<=zu;++Z)
{
printf("Case %d: ",Z);
scanf("%d%d%d",&N,&M,&K);
Init_MCMF();
for(int i=1;i<=N;++i) scanf("%d",&A[i]),sum+=A[i];
for(int i=1;i<=M;++i)
{
scanf("%d%d",&B,&C);
AddEdge(S,i+(N<<1),B,C);
AddEdge(i+(N<<1),Hos,INF,0);
}
for(int i=1;i<=K;++i) scanf("%d%d",&D[i],&E[i]);
for(int i=1;i<=N;++i)
{
AddEdge(S,i,A[i],0);
AddEdge(i+N,T,A[i],0);
AddEdge(Hos,i+N,INF,0);
if(i+1<=N) AddEdge(i,i+1,INF,0);
for(int j=1;j<=K;++j)
if(i+D[j]+1<=N)
AddEdge(i,i+D[j]+1+N,INF,E[j]);
}
Mincost();
}
return 0;
}