树形DP+树状数组 HDU 5877 Weak Pair

 //树形DP+树状数组 HDU 5877  Weak Pair
 // 思路：用树状数组每次加k/a[i]，每个节点ans+=Sum(a[i]) 表示每次加大于等于a[i]的值
 // 这道题要离散化

 #include <bits/stdc++.h>
 using namespace std;
 #define LL long long
 typedef pair<int,int> pii;
 const double inf = 123456789012345.0;
 const LL MOD =100000000LL;
 const int N = 2e5+;
 const int maxx = ;
 #define clc(a,b) memset(a,b,sizeof(a))
 const double eps = 1e-;
 void fre() {freopen("in.txt","r",stdin);}
 void freout() {freopen("out.txt","w",stdout);}
 inline int read() {int x=,f=;char ch=getchar();while(ch>''||ch<'') {if(ch=='-') f=-; ch=getchar();}while(ch>=''&&ch<='') {x=x*+ch-'';ch=getchar();}return x*f;}

 map<LL,LL> ma;
 LL a[N];
 LL c[N],b[N];
 LL in[N];
 vector<LL> g[N];
 LL lowbit(LL x){ return x&(-x);}
 LL add(LL x,int t){
     while(x>){
        c[x]+=t;
        x-=lowbit(x);
     }
 }
 LL Sum(LL x){
     LL sum=;
     while(x<maxx){
         sum+=c[x];
         x+=lowbit(x);
     }
     return sum;
 }

 LL ans=;
 LL n,k;
 void dfs(LL rt){
      for(LL i=;i<(int)g[rt].size();i++){
          LL v=g[rt][i];
          ans+=Sum(ma[a[v]]);
          if(a[v]==) add(maxx,);
          else add(ma[k/a[v]],);
          dfs(v);
          if(a[v]==) add(maxx,-);
          else add(ma[k/a[v]],-);
      }
 }
 int main(){
     int T;
     scanf("%d",&T);
     while(T--){
         ma.clear();
         memset(c,,sizeof(c));
         scanf("%I64d%I64d",&n,&k);
         for(int i=;i<=n;i++){
             scanf("%I64d",&a[i]);
             b[i*-]=a[i];
             if(a[i]!=) b[i*-]=k/a[i];
             g[i].clear();
             in[i]=;
         }
         sort(b,b+*n);
         int K=unique(b,b+*n)-b;
         int cxt=;
         for(int i=;i<K;i++){
             ma[b[i]]=++cxt;
         }
         for(LL i=;i<n-;i++){
             LL u,v;
             scanf("%I64d%I64d",&u,&v);
             g[u].push_back(v);
             in[v]++;
         }
         LL rt;
         for(LL i=;i<=n;i++){
             if(in[i]==){
                 rt=i;
                 break;
             }
         }
         ans=;
         if(a[rt]==) add(maxx,);
         else add(ma[k/a[rt]],);
         dfs(rt);
         printf("%I64d\n",ans);
     }
     return ;
 }