BZOJ2502: 清理雪道

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cmath>
  4 #include<cstring>
  5 #include<algorithm>
  6 #include<iostream>
  7 #include<vector>
  8 #include<map>
  9 #include<set>
 10 #include<queue>
 11 #include<string>
 12 #define inf 1000000000
 13 #define maxn 100000
 14 #define maxm 100000
 15 #define eps 1e-10
 16 #define ll long long
 17 #define pa pair<int,int>
 18 #define for0(i,n) for(int i=0;i<=(n);i++)
 19 #define for1(i,n) for(int i=1;i<=(n);i++)
 20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
 21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
 22 #define for4(i,x) for(int i=head[x],y;i;i=e[i].next)
 23 #define mod 1000000007
 24 using namespace std;
 25 inline int read()
 26 {
 27     int x=0,f=1;char ch=getchar();
 28     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 29     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
 30     return x*f;
 31 }
 32 int  n,m,s,t,ss,tt,in[maxn],maxflow,tot=1,head[maxn],cur[maxn],h[maxn];
 33 queue<int>q;
 34 struct edge{int go,next,v;}e[maxm];
 35 inline void ins(int x,int y,int v)
 36 {
 37     e[++tot]=(edge){y,head[x],v};head[x]=tot;
 38     e[++tot]=(edge){x,head[y],0};head[y]=tot;
 39 }
 40 inline void insert(int x,int y,int l,int r)
 41 {
 42     in[y]+=l;in[x]-=l;ins(x,y,r-l);
 43 }
 44 void build()
 45 {
 46     for0(i,tt)if(in[i]>0)ins(ss,i,in[i]);else if(in[i]<0)ins(i,tt,-in[i]);
 47 }
 48 bool bfs()
 49 {
 50     for(int i=0;i<=tt;i++)h[i]=-1;
 51     q.push(s);h[s]=0;
 52     while(!q.empty())
 53     {
 54         int x=q.front();q.pop();
 55         for(int i=head[x];i;i=e[i].next)
 56          if(e[i].v&&h[e[i].go]==-1)
 57          {
 58             h[e[i].go]=h[x]+1;q.push(e[i].go);
 59          }
 60     }
 61     return h[t]!=-1;
 62 }
 63 int dfs(int x,int f)
 64 {
 65     if(x==t) return f;
 66     int tmp,used=0;
 67     for(int i=cur[x];i;i=e[i].next)
 68      if(e[i].v&&h[e[i].go]==h[x]+1)
 69     {
 70         tmp=dfs(e[i].go,min(e[i].v,f-used));
 71         e[i].v-=tmp;if(e[i].v)cur[x]=i;
 72         e[i^1].v+=tmp;used+=tmp;
 73         if(used==f)return f;       
 74     }
 75     if(!used) h[x]=-1;
 76     return used;
 77 }
 78 void dinic()
 79 {
 80     maxflow=0;
 81     while(bfs())
 82     {
 83         for (int i=0;i<=tt;i++)cur[i]=head[i];maxflow+=dfs(s,inf);
 84     }
 85 }
 86 int minflow()
 87 {
 88     s=ss;t=tt;
 89     dinic();
 90     int ans=e[tot].v;
 91     e[tot].v=e[tot^1].v=0;
 92     s=n+1;t=0;
 93     dinic();
 94     return ans-maxflow;
 95 }
 96 int main()
 97 {
 98     freopen("input.txt","r",stdin);
 99     freopen("output.txt","w",stdout);
100     n=read();
101     for1(i,n)
102     {
103         int x=read();
104         for1(j,x)insert(i,read(),1,inf);
105     }
106     s=0;t=n+1;ss=t+1;tt=t+2;
107     for1(i,n)insert(s,i,0,inf),insert(i,t,0,inf);
108     build();
109     insert(t,s,0,inf);
110     printf("%d\n",minflow());    
111     return 0;
112 }