题意：求区间【a，b】的第k大
因为多次询问要用到划分树
#include <iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define MAXN 100010
int tree[30][MAXN],sorted[MAXN];
int toleft[30][MAXN];
void build(int l,int r,int dep){
if(l==r)return;
int i;
int mid=(l+r)>>1;
int same=mid-l+1;
for(i=l;i<=r;i++)
if(tree[dep][i]<sorted[mid])
same--;
int lpos=l;
int rpos=mid+1;
for(i=l;i<=r;i++){
if(tree[dep][i]<sorted[mid])
tree[dep+1][lpos++]=tree[dep][i];
else if(tree[dep][i]==sorted[mid]&&same>0){
tree[dep+1][lpos++]=tree[dep][i];
same--;
}
else
tree[dep+1][rpos++]=tree[dep][i];
toleft[dep][i]=toleft[dep][l-1]+lpos-l;//左边的个数
}
build(l,mid,dep+1);
build(mid+1,r,dep+1);
}
int query(int L,int R,int l,int r,int dep,int k){
if(l==r)return tree[dep][l];
int mid=(L+R)>>1;
int cnt=toleft[dep][r]-toleft[dep][l-1];
if(cnt>=k){
int newl=L+toleft[dep][l-1]-toleft[dep][L-1];
int newr=newl+cnt-1;
return query(L,mid,newl,newr,dep+1,k);
}else{
int newr=r+toleft[dep][R]-toleft[dep][r];
int newl=newr-(r-l-cnt);
return query(mid+1,R,newl,newr,dep+1,k-cnt);
}
}
int main(int argc, char** argv) {
int v,n,m,i;
int s,t,k;
scanf("%d",&v);
while(v--){
scanf("%d%d",&n,&m);
memset(tree,0,sizeof(tree));
memset(toleft,0,sizeof(toleft));
for(i=1;i<=n;i++){
scanf("%d",&tree[0][i]);
sorted[i]=tree[0][i];
}
sort(sorted+1,sorted+n+1);
build(1,n,0);
while(m--){
scanf("%d%d%d",&s,&t,&k);
printf("%d\n",query(1,n,s,t,0,k));
}
}
return 0;
}