K

kd树模板题目，建立kd树，对于每个输入进行搜索，在原来的基础上加入价格比对就可以了。

kd树其实就是一种暴力＋减枝的操作。

#include <algorithm>#include <bitset>#include <cassert>#include <climits>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <deque>#include <iomanip>#include <iostream>#include <map>#include <numeric>#include <queue>#include <set>#include <stack>#include <string>#include <math.h>#include <set>#include <vector>using namespace std;#define Max_N (200000 + 100)#define Max_M (20000 + 100)#define ll long long intconst ll INF = 1e17;struct P{    int p[2], c, id;};P h[Max_N];#define de 2double var[de];int split[Max_N];int CM;bool cmp(const P &a, const P &b){    return a.p[CM] < b.p[CM];}void KD_build(int l, int r){    if (l >= r) return;    int mid = l + (r - l) / 2;    for (int i = 0; i < de; i++) {        double ave = 0;        for (int j = l; j <= r; j++) {            ave += h[j].p[i];        }        ave /= (r - l + 1);        var[i] = 0;        for (int j = l; j <= r; j++) {            var[i] += (h[j].p[i] - ave) * (h[j].p[i] - ave);        }        var[i] /= (r - l + 1);    }    split[mid] = -1;    double ms = -1;    for (int i = 0; i < de; i++) {        if (var[i] > ms) {            split[mid] = i;            ms = var[i];        }    }    CM = split[mid];    nth_element(h+l,h+mid,h+r+1,cmp);    KD_build(l,mid-1);    KD_build(mid+1,r);    }int ans_i;ll ansdis;void KD_query(int l, int r, P s){    int mid = l + (r - l) / 2;    if (l > r) return;    long long int dis = 0;    for (int i = 0; i < de; i++) {        dis += (ll)(s.p[i] - h[mid].p[i]) * (s.p[i] - h[mid].p[i]);    }    if (h[mid].c <= s.c) {        if (ansdis == dis && h[mid].id < h[ans_i].id) {            ans_i = mid;        }        if (ansdis > dis) {            ansdis = dis;            ans_i = mid;        }    }    int d = split[mid];    ll radius = (ll)(s.p[d] - h[mid].p[d]) * (s.p[d] - h[mid].p[d]);    if (s.p[d] < h[mid].p[d]) {        KD_query(l, mid-1, s);        if (ansdis >= radius) {            KD_query(mid+1, r, s);        }    }    else {        KD_query(mid+1, r, s);        if (ansdis >= radius) {            KD_query(l, mid-1, s);        }    }}int main(){    int T, n, m;    scanf("%d", &T);    while (T--) {        scanf("%d%d", &n, &m);        for (int i = 0; i < n; i++) {            scanf("%d%d%d", &h[i].p[0], &h[i].p[1], &h[i].c);            h[i].id = i;        }        KD_build(0, n-1);        P s;        for (int i = 0; i < m; i++) {            scanf("%d%d%d", &s.p[0], &s.p[1], &s.c);            ansdis = INF;            ans_i = -1;            KD_query(0, n-1, s);            printf("%d %d %d\n", h[ans_i].p[0], h[ans_i].p[1], h[ans_i].c);        }    }    return 0;}