NOIP2015BLOCKADE c++ 代码

  1 #include<algorithm>
  2 #include<fstream>
  3 #include<functional>
  4 #include<iostream>
  5 using namespace std;
  6 static const int N=50001;
  7 typedef long long int64;
  8 struct node
  9 {
 10     int v,w;
 11     node *next;
 12 }alist[3*N];
 13 struct heapnode
 14 {
 15     int64 w;
 16     int u;
 17     bool operator>(const heapnode &r)const 
 18     {
 19         return w>r.w;
 20     }
 21 };
 22 int p[N][19];
 23 int64 w[N][19];
 24 void dfs1(int u)
 25 {
 26     for(node *i=alist[u].next;i;i=i->next)
 27         if(i->v!=p[u][0])
 28         {
 29             p[i->v][0]=u;
 30             w[i->v][0]=i->w;
 31             dfs1(i->v);
 32         }
 33 }
 34 bool visit[N];
 35 void dfs2(int u)
 36 {
 37     if(visit[u])return;
 38     if(!alist[u].next->next)return;
 39     visit[u]=true;
 40     for(node *i=alist[u].next;i;i=i->next)
 41         if(i->v!=p[u][0])
 42         {
 43             dfs2(i->v);
 44             if(!visit[i->v])
 45             {
 46                 visit[u]=false;
 47                 break;
 48             }
 49         }
 50 }
 51 int main()
 52 {
 53     ifstream fin("blockade.in");
 54     ofstream fout("blockade.out");
 55     int n(0),m(0);
 56     fin>>n;
 57     node *anode(alist+n+1);
 58     for(int i=0;i<n-1;i++)
 59     {
 60         int u(0),v(0),ww(0);
 61         fin>>u>>v>>ww;
 62         anode->v=v;
 63         anode->w=ww;
 64         anode->next=alist[u].next;
 65         alist[u].next=anode++;
 66         anode->v=u;
 67         anode->w=ww;
 68         anode->next=alist[v].next;
 69         alist[v].next=anode++;
 70     }
 71     fin>>m;
 72     static int d[N];
 73     for(int i=0;i<m;i++)
 74         fin>>d[i];
 75     int NScount=0;
 76     for(node *i=alist[1].next;i;i=i->next)
 77     {
 78         NScount++;
 79         p[i->v][0]=1;
 80         w[i->v][0]=i->w;
 81         dfs1(i->v);
 82     }
 83     if(NScount>m)
 84     {
 85         fout<<"-1"<<endl;
 86         return 0;
 87     }
 88     for(int j=1;j<=18;j++)
 89         for(int i=1;i<=n;i++)
 90         {
 91             p[i][j]=p[p[i][j-1]][j-1];
 92             w[i][j]=w[i][j-1]+w[p[i][j-1]][j-1];
 93         }
 94     static heapnode a[N],b[N];
 95     heapnode *atop(0),*aback(0),*btop(0),*bback(0);
 96     static int _w[N];
 97     for(node *i=alist[1].next;i;i=i->next)
 98         _w[i->v]=i->w;
 99     int64 l(0),r(1e16),ans(1e16);
100     greater<heapnode> comp;
101     while(l<=r)
102     {
103         atop=a;
104         aback=a;
105         btop=b;
106         bback=b;
107         int64 mm=(l+r)>>1;
108         for(int i=1;i<=n;i++)
109             visit[i]=false;
110         for(int i=0;i<m;i++)
111         {
112             int u=d[i];
113             int64 ww=mm;
114             for(int j=18;j>=0;j--)
115                 if(p[u][j]&&p[u][j]!=1&&ww>=w[u][j])
116                 {
117                     ww-=w[u][j];
118                     u=p[u][j];
119                 }
120             if(/*p[u][0]==1&&*/ww>w[u][0])
121             {
122                 aback->w=ww-w[u][0];
123                 aback->u=u;
124                 aback++;
125                 push_heap(atop,aback,comp);
126             }
127             else visit[u]=true;
128         }
129         dfs2(1);
130         if(visit[1])
131         {
132             ans=mm;
133             r=mm-1;
134         }
135         else
136         {
137             for(node *i=alist[1].next;i;i=i->next)
138                 if(!visit[i->v])
139                 {
140                     bback->w=i->w;
141                     bback->u=i->v;
142                     bback++;
143                     push_heap(btop,bback,comp);
144                 }
145             while(btop!=bback||atop!=aback)
146             {
147                 while(atop!=aback&&!visit[atop->u]&&atop->w<_w[atop->u])
148                 {
149                     visit[atop->u]=true;
150                     pop_heap(atop,aback,comp);
151                     aback--;
152                 }
153                 while(btop!=bback&&visit[btop->u])
154                 {
155                     pop_heap(btop,bback,comp);
156                     bback--;
157                 }
158                 if(btop==bback||atop==aback)break;
159                 if(atop->w>=btop->w)
160                 {
161                     visit[btop->u]=true;
162                     pop_heap(atop,aback,comp);
163                     aback--;
164                     pop_heap(btop,bback,comp);
165                     bback--;
166                 }
167                 else
168                 {
169                     pop_heap(atop,aback,comp);
170                     aback--;
171                 }
172             }
173             if(btop==bback)
174             {
175                 ans=min(ans,mm);
176                 r=mm-1;
177             }
178             else l=mm+1;
179         }
180     }
181     fout<<ans<<endl;
182     return 0;
183 }