POJ 1442 Treap模板

// by SiriusRen
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int cnt=0,jy,a[30500],n,m,root=-1;
struct node{
int left,right,count_left,count_right,key,priority;
}treap[30500];
void zig(int &x){
int y=treap[x].right;
treap[x].right=treap[y].left;
treap[x].count_right=treap[y].count_left;
treap[y].left=x;
treap[y].count_left=treap[x].count_left+treap[x].count_right+1;
x=y;
}
void zag(int &x){
int y=treap[x].left;
treap[x].left=treap[y].right;
treap[x].count_left=treap[y].count_right;
treap[y].right=x;
treap[y].count_right=treap[x].count_left+treap[x].count_right+1;
x=y;
}
void insert(int &x,int new_key){
if(x==-1){
x=cnt++;
treap[x].left=treap[x].right=-1;
treap[x].priority=rand();
treap[x].key=new_key;
treap[x].count_left=treap[x].count_right=0;
}
else if(new_key<treap[x].key){
treap[x].count_left++;
insert(treap[x].left,new_key);
if(treap[x].priority>treap[treap[x].left].priority)zag(x);
}
else{
treap[x].count_right++;
insert(treap[x].right,new_key);
if(treap[x].priority>treap[treap[x].right].priority)zig(x);
}
}
int query(int &x,int k_th){
if(treap[x].count_left+1==k_th)return treap[x].key;
if(treap[x].count_left+1<k_th)return query(treap[x].right,k_th-treap[x].count_left-1);
return query(treap[x].left,k_th);
}
int main(){
scanf("%d%d",&n,&m);
for(int i=1;i<=n;i++)scanf("%d",&a[i]);
for(int i=1;i<=m;i++){
scanf("%d",&jy);
while(cnt<jy)insert(root,a[cnt+1]);
printf("%d\n",query(root,i));
}
}