poj 3714 分治加剪枝

//A#define _CRT_SECURE_NO_WARNINGS#include <cstdio>#include <cmath>#include <algorithm>#include<algorithm>using namespace std;const double MAX_DIST = 1e100;const int MAXN = 200010;struct Point {double x, y;bool flag;};inline double dist(const Point &a, const Point &b) {if (a.flag != b.flag)return  sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));elsereturn MAX_DIST;}Point pt[MAXN];int y_sort[MAXN];inline bool x_cmp(const Point &a, const Point &b) {return a.x < b.x;}inline bool y_cmp(const int &a, const int &b) {return pt[a].y < pt[b].y;}double shortest_distance(int left, int right) {if (right - left == 1)return dist(pt[left], pt[right]);else if (right - left == 2)return min(min(dist(pt[left], pt[left + 1]), dist(pt[left], pt[left + 2])),dist(pt[left + 1], pt[left + 2]));int mid = (left + right) >> 1;double mind = min(shortest_distance(left, mid), shortest_distance(mid + 1, right));if (mind == 0) return 0;int yn = 0;for (int i = mid; pt[mid].x - pt[i].x < mind && i >= left; --i)y_sort[yn++] = i;int y_mid = yn;for (int i = mid + 1; pt[i].x - pt[mid].x < mind && i <= right; ++i)y_sort[yn++] = i;for (int i = 0; i < y_mid; ++i) for (int j = y_mid; j < yn; ++j)mind = min(mind, dist(pt[y_sort[i]], pt[y_sort[j]]));return mind;}int main() {int T;scanf("%d", &T);while (T--) {int n;scanf("%d", &n);for (int i = 0; i < n; ++i) {scanf("%lf%lf", &pt[i].x, &pt[i].y);pt[i].flag = false;}for (int i = n; i < 2 * n; ++i) {scanf("%lf%lf", &pt[i].x, &pt[i].y);pt[i].flag = true;}sort(pt, pt + 2 * n, x_cmp);printf("%.3f\n", shortest_distance(0, 2 * n - 1));}}