【牛客网】Finding Hotel

忘记K远点对的剪枝的我有点自闭

事实上我们只要先建一棵KD树出来，维护一下所在的矩形，和子树里的最小值

每次查询的时候如果最小值比查询的值要大的话就退出

当前的答案构成了一个圆，若圆和矩形没有交就退出（不一定很严格，可以认为是以圆心为中心向上下左右延伸半径长度的一个正方形和矩形有交）

然后看当前点在哪个子树的矩形里，先搜那个子树，如果回来后在另一个子树里可能达到的最小值都没有答案大就不搜索另一棵子树

#include <bits/stdc++.h>

#define fi first

#define se second

#define pii pair<int,int>

#define mp make_pair

#define pb push_back

#define space putchar(' ')

#define enter putchar('\n')

#define eps 1e-10

#define ba 47

#define MAXN 200005

//#define ivorysi

using namespace std;

typedef long long int64;

typedef unsigned int u32;

typedef double db;

template<class T>

    void read(T &res) {

    res = 0;T f = 1;char c = getchar();

    while(c < '0' || c > '9') {

        if(c == '-') f = -1;

        c = getchar();

    }

    while(c >= '0' && c <= '9') {

        res = res * 10 +c - '0';

        c = getchar();

    }

    res *= f;

}

template<class T>

    void out(T x) {

    if(x < 0) {x = -x;putchar('-');}

    if(x >= 10) {

        out(x / 10);

    }

    putchar('0' + x % 10);

}

int N,dimension,M,rt,Ncnt;

struct node {

    int d[2],c,id;

}p[MAXN];

bool cmp(node a,node b) {

    return a.d[dimension] < b.d[dimension];

}

struct KD {

    node p;

    int r[4],lc,rc,mc;

}tr[MAXN];

#define lc(u) tr[u].lc

#define rc(u) tr[u].rc

void build(int &u,int l,int r,int d) {

    u = 0;

    if(l > r) return;

    u = ++Ncnt;

    dimension = d;

    int mid = (l + r) >> 1;

    nth_element(p + l,p + mid,p + r + 1,cmp);

    tr[u].p = p[mid];

    for(int i = 0 ; i < 4 ; ++i) tr[u].r[i] = tr[u].p.d[i & 1];

    build(lc(u),l,mid - 1,d ^ 1);build(rc(u),mid + 1,r,d ^ 1);

    tr[u].mc = min(p[mid].c,min(tr[lc(u)].mc,tr[rc(u)].mc));

    for(int i = 0 ; i < 2 ; ++i) tr[u].r[i] = min(tr[u].r[i],min(tr[lc(u)].r[i],tr[rc(u)].r[i]));

    for(int i = 2 ; i < 4 ; ++i) tr[u].r[i] = max(tr[u].r[i],max(tr[lc(u)].r[i],tr[rc(u)].r[i]));

}

node ans;

int64 o(int64 x) {return x * x;}

int64 dis(node a,node b) {

    return o(a.d[0] - b.d[0]) + o(a.d[1] - b.d[1]);

}

bool checkin(node x,int u) {

    for(int i = 0 ; i <= 1 ; ++i) {

        if(x.d[i] < tr[u].r[i] || x.d[i] > tr[u].r[i | 2]) return false;

    }

    return true;

}

int64 min_possible(node x,int u) {

    for(int i = 0 ; i <= 1 ; ++i) {

        if(x.d[i] < tr[u].r[i] || x.d[i] > tr[u].r[i | 2]) {

            return min(o(tr[u].r[i] - x.d[i]),o(tr[u].r[i | 2] - x.d[i]));

        }

    }

    return 1e18;

}

void Query(int u,node pos) {

    if(!u) return;

    if(tr[u].mc > pos.c) return;

    if(tr[u].p.c <= pos.c) {

        if(dis(tr[u].p,pos) < dis(ans,pos) || (dis(tr[u].p,pos) == dis(ans,pos) && tr[u].p.id < ans.id)) ans = tr[u].p;

    }

    int64 d = dis(ans,pos);

    for(int i = 0 ; i <= 1 ; ++i) {

        if(pos.d[i] < tr[u].r[i] && 1LL * (tr[u].r[i] - pos.d[i]) * (tr[u].r[i] - pos.d[i]) > d) return;

        if(pos.d[i] > tr[u].r[i | 2] && 1LL * (tr[u].r[i | 2] - pos.d[i]) * (tr[u].r[i | 2] - pos.d[i]) > d) return;

    }

    int s = checkin(pos,lc(u)) ? lc(u) : rc(u);

    int t = s == lc(u) ? rc(u) : lc(u);

    Query(s,pos);

    if(min_possible(pos,t) <= dis(pos,ans)) Query(t,pos);

}

void Solve() {

    rt = 0;Ncnt = 0;

    read(N);read(M);

    for(int i = 1 ; i <= N ; ++i) {

        read(p[i].d[0]);read(p[i].d[1]);read(p[i].c);

        p[i].id = i;

    }

    tr[0].mc = 1e9;

    tr[0].r[0] = tr[0].r[1] = 1e9;

    tr[0].r[2] = tr[0].r[3] = -1;

    build(rt,1,N,0);

    node pos;

    for(int i = 1 ; i <= M ; ++i) {

        read(pos.d[0]);read(pos.d[1]);read(pos.c);

        ans.d[0] = 1e9;ans.d[1] = 1e9;ans.c = 0;ans.id = 1e9;

        Query(1,pos);

        out(ans.d[0]);space;out(ans.d[1]);space;out(ans.c);enter;

    }

}

int main(){

    #ifdef ivorysi

    freopen("f1.in","r",stdin);

    #endif

    int T;

    read(T);

    while(T--) Solve();

    return 0;

}

巴特西

【牛客网】Finding Hotel

【牛客网】Finding Hotel

最新文章

热门文章