【BZOJ1803】Spoj1487 Query on a tree III

Description

You are given a node-labeled rooted tree with n nodes. Define the query (x, k): Find the node whose label is k-th largest in the subtree of the node x. Assume no two nodes have the same labels.

Input

The first line contains one integer n (1 <= n <= 10^5). The next line contains n integers li (0 <= li <= 109) which denotes the label of the i-th node. Each line of the following n - 1 lines contains two integers u, v. They denote there is an edge between node u and node v. Node 1 is the root of the tree. The next line contains one integer m (1 <= m <= 10^4) which denotes the number of the queries. Each line of the next m contains two integers x, k. (k <= the total node number in the subtree of x)

Output

For each query (x, k), output the index of the node whose label is the k-th largest in the subtree of the node x.

Sample Input

5

1 3 5 2 7

1 2

2 3

1 4

3 5

4

2

3

4 1

3 2

3 2

Sample Output

5 4 5 5

题解：这样例你告诉我是求子树第k大？（the k_th largest）分明是第k小啊！

直接主席树+DFS序搞定。

#include 
     
       #include 
      
        #include 
       
         #include 
        
          using namespace std; const int maxn=100010; int n,m,cnt,tot; int to[maxn<<1],next[maxn<<1],head[maxn],v[maxn],p[maxn],q[maxn],rt[maxn]; int ls[maxn*30],rs[maxn*30],siz[maxn*30],s[maxn*30]; struct number {     int val,org; }num[maxn]; bool cmp(number a,number b) {     return a.val
         
          r)  return ;     y=++tot,siz[y]=siz[x]+1;     if(l==r)     {         s[y]=b;         return ;     }     int mid=l+r>>1;     if(a<=mid)   rs[y]=rs[x],insert(ls[x],ls[y],l,mid,a,b);     else    ls[y]=ls[x],insert(rs[x],rs[y],mid+1,r,a,b); } int query(int a,int b,int l,int r,int c) {     if(l==r)    return s[a];     int mid=l+r>>1,sm=siz[ls[a]]-siz[ls[b]];     if(c<=sm)    return query(ls[a],ls[b],l,mid,c);     else    return query(rs[a],rs[b],mid+1,r,c-sm); } void dfs(int x,int fa) {     p[x]=++p[0];     insert(rt[p[0]-1],rt[p[0]],1,n,v[x],x);     for(int i=head[x];i!=-1;i=next[i])  if(to[i]!=fa)   dfs(to[i],x);     q[x]=p[0]; } void add(int a,int b) {     to[cnt]=b,next[cnt]=head[a],head[a]=cnt++; } int main() {     scanf("%d",&n);     int i,a,b;     for(i=1;i<=n;i++)    scanf("%d",&num[i].val),num[i].org=i;     sort(num+1,num+n+1,cmp);     for(i=1;i<=n;i++)    v[num[i].org]=i;     memset(head,-1,sizeof(head));     for(i=1;i