【费用流】bzoj1520 [POI2006]Szk-Schools

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<queue>
 5 using namespace std;
 6 #define MAXN 5001
 7 #define MAXM 100001
 8 #define INF 2147483647
 9 int S,T,n,x,A,B,C;
10 int en,u[MAXM],v[MAXM],first[MAXN],next[MAXM],cap[MAXM],cost[MAXM];//Next Array
11 bool inq[MAXN];
12 int d[MAXN]/*spfa*/,p[MAXN]/*spfa*/,a[MAXN]/*可改进量*/;
13 queue<int>q;
14 void Init_MCMF(){memset(first,-1,sizeof(first));en=0;S=0;T=(n<<1|1);}
15 void AddEdge(const int &U,const int &V,const int &W,const int &C)
16 {
17     u[en]=U; v[en]=V; cap[en]=W; cost[en]=C;
18     next[en]=first[U]; first[U]=en++;
19     u[en]=V; v[en]=U; cost[en]=-C;
20     next[en]=first[V]; first[V]=en++;
21 }
22 bool Spfa(int &Flow,int &Cost)
23 {
24     memset(d,0x7f,sizeof(d));
25     memset(inq,0,sizeof(inq));
26     d[S]=0; inq[S]=1; p[S]=0; a[S]=INF; q.push(S);
27     while(!q.empty())
28       {
29         int U=q.front(); q.pop(); inq[U]=0;
30         for(int i=first[U];i!=-1;i=next[i])
31           if(cap[i] && d[v[i]]>d[U]+cost[i])
32             {
33               d[v[i]]=d[U]+cost[i];
34               p[v[i]]=i;
35               a[v[i]]=min(a[U],cap[i]);
36               if(!inq[v[i]]) {q.push(v[i]); inq[v[i]]=1;}
37             }
38       }
39     if(d[T]>2000000000) return 0;
40     Flow+=a[T]; Cost+=d[T]*a[T]; int U=T;
41     while(U!=S)
42       {
43         cap[p[U]]-=a[T]; cap[p[U]^1]+=a[T];
44         U=u[p[U]];
45       }
46     return 1;
47 }
48 void Mincost()
49 {
50     int Flow=0,Cost=0;
51     while(Spfa(Flow,Cost));
52     if(Flow==n) printf("%d\n",Cost);
53     else puts("NIE");
54 }
55 int Abs(const int &v){return v<0 ? -v : v;}
56 int main()
57 {
58     scanf("%d",&n); Init_MCMF();
59     for(int j=1;j<=n;++j)
60       {
61           scanf("%d%d%d%d",&x,&A,&B,&C);
62           AddEdge(S,j,1,0);
63           for(int i=A;i<=B;++i) AddEdge(j,i+n,1,Abs(i-x)*C);
64       }
65     for(int i=1;i<=n;++i) AddEdge(i+n,T,1,0);
66     Mincost();
67     return 0;
68 }