hdu 2665 划分树

思路：裸的划分树

#include<iostream>

#include<algorithm>

#include<cstring>

#include<cstdio>

#include<algorithm>

#include<cmath>

#define Maxn 100010

#define inf 0x7fffffff

#define lson(x) (x<<1)

#define rson(x) ((x<<1)|1)

#define mid ((tree[po].l+tree[po].r)>>1)

using namespace std;

struct Tree{

    int l,r;

}tree[Maxn*4];

int sorted[Maxn];

int val[20][Maxn],toLeft[20][Maxn];

void BuildTree(int l,int r,int dep,int po)

{

    tree[po].l=l,tree[po].r=r;

    if(l==r) return ;

    int same=mid-l+1,i;

    for(i=l;i<=r;i++)

        if(val[dep][i]<sorted[mid])

            same--;

    int lpos=l,rpos=mid+1;

    for(i=l;i<=r;i++)

    {

        if(i==l)

            toLeft[dep][i]=0;

        else

            toLeft[dep][i]=toLeft[dep][i-1];

        if(val[dep][i]<sorted[mid])

            toLeft[dep][i]++,val[dep+1][lpos++]=val[dep][i];

        else

            if(val[dep][i]>sorted[mid])

            val[dep+1][rpos++]=val[dep][i];

        else

            if(same)

            toLeft[dep][i]++,val[dep+1][lpos++]=val[dep][i],same--;

            else

            val[dep+1][rpos++]=val[dep][i];

    }

    BuildTree(l,mid,dep+1,lson(po));

    BuildTree(mid+1,r,dep+1,rson(po));

}

int query(int l,int r,int k,int dep,int po)

{

    if(l==r)

        return val[dep][l];

    int vd,invd;

    if(l==tree[po].l)

        vd=toLeft[dep][r],invd=0;

    else

        vd=toLeft[dep][r]-toLeft[dep][l-1],invd=toLeft[dep][l-1];

    if(vd>=k){

        int newl=tree[po].l+invd;

        int newr=tree[po].l+vd+invd-1;

        return query(newl,newr,k,dep+1,lson(po));

    }

    else{

        int ss=l-tree[po].l-invd;

        int s=r-l+1-vd;

        int newl=mid+ss+1;

        int newr=mid+ss+s;

        return query(newl,newr,k-vd,dep+1,rson(po));

    }

}

int main()

{

    int n,m,i,j,k,s,t,T;

    scanf("%d",&T);

    while(T--)

    {

        scanf("%d%d",&n,&m);

        for(i=1;i<=n;i++)

        {

            scanf("%d",&val[0][i]);

            sorted[i]=val[0][i];

        }

        sort(sorted+1,sorted+1+n);

        BuildTree(1,n,0,1);

        for(i=1;i<=m;i++)

        {

            scanf("%d%d%d",&s,&t,&k);

            printf("%d\n",query(s,t,k,0,1));

        }

    }

    return 0;

}