bzoj 1834: [ZJOI2010]network 网络扩容

Posted 2020-06-23 xiyuedong

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<cstring>
  4 #define M 100000
  5 #define inf 2139062143
  6 using namespace std;
  7 struct data
  8 {
  9     int l,r,w;
 10 }a[M];
 11 int q[M],d[M],head[M],next[10*M],u[10*M],v[10*M],cnt=1,n,m,K,ans;
 12 int cnt1=1,head1[M],next1[10*M],fro[10*M],u1[10*M],v1[10*M],w1[10*M],f[M],fr[M];
 13 void jia(int a1,int a2,int a3)
 14 {
 15     cnt++;
 16     u[cnt]=a2;
 17     v[cnt]=a3;
 18     next[cnt]=head[a1];
 19     head[a1]=cnt;
 20 }
 21 void jia1(int a1,int a2,int a3,int a4)
 22 {
 23     cnt1++;
 24     fro[cnt1]=a1;
 25     u1[cnt1]=a2;
 26     v1[cnt1]=a3;
 27     w1[cnt1]=a4;
 28     next1[cnt1]=head1[a1];
 29     head1[a1]=cnt1;
 30 }
 31 bool bfs()
 32 {
 33     memset(d,0,sizeof(int)*(2*n));
 34     int h=0,t=1;
 35     q[1]=1;
 36     d[1]=1;
 37     for(;h<t;)
 38       {
 39         h++;
 40         int p=q[h];
 41         for(int i=head[p];i;i=next[i])
 42           if(!d[u[i]]&&v[i])
 43             {
 44                 d[u[i]]=d[p]+1;
 45                 if(d[n])
 46                   return 1;
 47                 t++;
 48                 q[t]=u[i];
 49             }
 50       }
 51     return 0;
 52 }
 53 int dinic(int s,int f)
 54 {
 55     if(s==n)
 56       return f;
 57     int rest=f;
 58     for(int i=head[s];i&&rest;i=next[i])
 59       if(v[i]&&d[u[i]]==d[s]+1)
 60         {
 61             int now=dinic(u[i],min(rest,v[i]));
 62             if(!now)
 63               d[u[i]]=0;
 64             v[i]-=now;
 65             v[i^1]+=now;
 66             rest-=now;
 67         }
 68     return f-rest;  
 69 }
 70 bool spfa()
 71 {
 72     memset(d,127,sizeof(int)*(2*n));
 73     d[0]=0;
 74     f[0]=1;
 75     q[1]=0;
 76     int h=0,t=1;
 77     for(;h<t;)
 78       {
 79         h++;
 80         int p=q[h];
 81         f[p]=0;
 82         for(int i=head1[p];i;i=next1[i])
 83           if(v1[i]&&d[u1[i]]>d[p]+w1[i])
 84             {
 85                 d[u1[i]]=d[p]+w1[i];
 86                 fr[u1[i]]=i;
 87                 if(!f[u1[i]])
 88                   {
 89                     f[u1[i]]=1;
 90                     t++;
 91                     q[t]=u1[i];
 92                     }
 93             }
 94       }
 95     if(d[n]!=inf)
 96       return 1;
 97     return 0;
 98 }
 99 void mcf()
100 {
101     int mx=inf;
102     for(int i=fr[n];i;i=fr[fro[i]])
103       mx=min(mx,v1[i]);
104     for(int i=fr[n];i;i=fr[fro[i]])
105       {
106         v1[i]-=mx;
107         v1[i^1]+=mx;
108         ans+=mx*(w1[i]);
109       }
110 }
111 int main()
112 {
113     scanf("%d%d%d",&n,&m,&K);
114     for(int i=1;i<=m;i++)
115       {
116         int a3;
117         scanf("%d%d%d%d",&a[i].l,&a[i].r,&a3,&a[i].w);
118         jia(a[i].l,a[i].r,a3);
119         jia(a[i].r,a[i].l,0);
120       }
121     for(;bfs();)
122       ans+=dinic(1,inf);
123     printf("%d ",ans);
124     for(int i=2;i<=cnt;i+=2)
125       {
126         jia1(a[i/2].l,a[i/2].r,inf,a[i/2].w);
127         jia1(a[i/2].r,a[i/2].l,0,-a[i/2].w);
128         jia1(a[i/2].l,a[i/2].r,v[i],0);
129         jia1(a[i/2].r,a[i/2].l,v[i+1],0);
130       }
131     jia1(0,1,K,0);
132     jia1(1,0,0,0);
133     ans=0;
134     for(;spfa();)
135       mcf();
136     printf("%d\n",ans);
137     return 0;
138 }

一遍最大流，一遍费用流。第一问跑完之后在残余网络建边，单位费用为扩容费用，