POJ 2104

#include<cstdio>
#include<algorithm>
#include<cstring>
#define N 100005
#define M N*20
using namespace std;
int n,m,Q,a[N],b[N],rt[N],pool;
int read()
{
    int ret=0,neg=1;char j=getchar();
    for (;j>‘9‘ || j<‘0‘;j=getchar()) if (j==‘-‘) neg=-1;
    for (;j>=‘0‘ && j<=‘9‘;j=getchar()) ret=ret*10+j-‘0‘;
    return ret*neg;
}
struct node
{
    int lc,rc,sum;
}t[M];
void disc_init()
{
    sort(b+1,b+m+1);
    m=unique(b+1,b+m+1)-b-1;
    for (int i=1;i<=n;i++)
        a[i]=lower_bound(b+1,b+m+1,a[i])-b;
}
void Insert(const int &y,int &x,const int &l,const int &r,const int &p)
{
    t[x=++pool]=t[y];
    ++t[x].sum;
    if (l==r) return;
    int mid=l+r>>1;
    if (p<=mid) Insert(t[y].lc,t[x].lc,l,mid,p);
    else Insert(t[y].rc,t[x].rc,mid+1,r,p);
}
int Query(const int &nl,const int &nr,const int &l,const int &r,const int &k)
{
    if (l==r) return l;
    int delta=t[t[nr].lc].sum-t[t[nl].lc].sum,mid=l+r>>1;
    if (delta>=k) return Query(t[nl].lc,t[nr].lc,l,mid,k);
    else return Query(t[nl].rc,t[nr].rc,mid+1,r,k-delta);
}
void tree_init()
{
    for (int i=1;i<=n;i++)
        Insert(rt[i-1],rt[i],1,m,a[i]);
}
int main()
{
    n=read(),Q=read(); 
    for (int i=1;i<=n;i++)
        a[i]=b[++m]=read();
    disc_init();
    tree_init();
    for (int i=1;i<=Q;i++)
    {
        int l=read(),r=read(),k=read();
        printf("%d\n",b[Query(rt[l-1],rt[r],1,m,k)]);
    } 
    return 0;
}