codevs 1218

  1 #include<bits/stdc++.h>
  2 #define inc(i,l,r) for(i=l;i<=r;i++)
  3 #define dec(i,l,r) for(i=l;i>=r;i--)
  4 #define mem(a) memset(a,0,sizeof(a))
  5 #define inf 1e9
  6 #define ll long long
  7 #define succ(x) (1<<x)
  8 #define NM 80000+5
  9 using namespace std;
 10 int read(){
 11     int x=0,f=1;char ch=getchar();
 12     while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
 13     while(isdigit(ch))x=x*10+ch-‘0‘,ch=getchar();
 14     return x*f;
 15 }
 16 struct edge{
 17     int t;
 18     ll v;
 19     edge *next;
 20 }e[2*NM],*h[NM];
 21 int f[NM][30],p=25,i,k,n,m,_x,_y,s,ff[NM],minn[NM];
 22 ll l,r,_t,b[NM],c[NM],d[NM][30],a[NM];
 23 bool v[NM],leaf[NM];
 24 multiset<ll>S;
 25 multiset<ll>::iterator it;
 26 void add(int x,int y,ll v){
 27     e[++s].t=y;e[s].v=v;e[s].next=h[x];h[x]=e+s;
 28 }
 29 void dfs(int x){
 30     v[x]++;
 31     inc(i,1,p){
 32         f[x][i]=f[f[x][i-1]][i-1];
 33         d[x][i]=d[f[x][i-1]][i-1]+d[x][i-1];
 34     }
 35     for(edge *j=h[x];j;j=j->next)
 36     if(!v[j->t]){
 37         leaf[x]=true;
 38         f[j->t][0]=x;
 39         d[j->t][0]=j->v;
 40         if(x==1){
 41         ff[j->t]=j->t;
 42         c[j->t]=j->v;
 43         }else ff[j->t]=ff[x];
 44         dfs(j->t);
 45     }
 46 }
 47 bool _dfs(int x,int k){
 48     if(!leaf[x]&&!v[x])return false;
 49     for(edge *j=h[x];j;j=j->next)
 50     if(j->t!=k&&!v[j->t])
 51     if(!_dfs(j->t,x))return false;
 52     return true;
 53 }
 54 bool check(){
 55     mem(v);mem(minn);mem(b);
 56     int num=0,tot=0;
 57     inc(i,1,m){
 58         ll t=_t,tmp=a[i];
 59         dec(k,p,0)
 60         if(t>=d[tmp][k]){
 61             t-=d[tmp][k];
 62             tmp=f[tmp][k];
 63         }
 64         if(tmp<=1){
 65             b[++tot]=t;
 66             if(t<=c[ff[a[i]]]&&(!minn[ff[a[i]]]||t<b[minn[ff[a[i]]]]))
 67             minn[ff[a[i]]]=tot;
 68         }else v[tmp]++;
 69     }
 70     for(edge *j=h[1];j;j=j->next)
 71     if(!v[j->t])v[j->t]=_dfs(j->t,1);
 72     inc(i,1,n)
 73     if(!v[i]&&minn[i])
 74     b[minn[i]]=0,v[i]++;
 75     sort(b+1,b+1+tot);
 76     S.clear();
 77 //    S.insert(-inf);S.insert(inf);
 78 //    printf("%d\n",S.size());
 79     for(edge *j=h[1];j;j=j->next)
 80     if(!v[j->t]){
 81     S.insert(j->v);
 82 //    printf("%d\n",S.size());
 83     }
 84     inc(i,1,tot)
 85     if(b[i]){
 86         it=S.upper_bound(b[i]);
 87         if(it==S.begin())continue;
 88         it--;
 89         S.erase(it);
 90 //        printf("%d\n",S.size());
 91         if(S.empty())return true;
 92     }
 93     return false;
 94  }
 95 int main(){
 96     n=read();
 97     inc(i,1,n-1){
 98         _x=read();_y=read();scanf("%lld",&_t);
 99         add(_x,_y,_t);add(_y,_x,_t);
100     }
101     dfs(1);
102     m=read();
103     inc(i,1,m)a[i]=read();
104     l=0;r=n*inf;
105     while(l+1<r){
106         _t=l+r>>1;
107         if(check())r=_t;else l=_t;
108     }
109     printf("%lld\n",r);
110     return 0;
111 }