袭击

 

 

#include <bits/stdc++.h>
using namespace std;
const int N = 200010;
double INF = 1e10;
struct Point {
    double x, y;
    bool type;
} points[N], temp[N];
//temp是用于归并
bool cmp(Point p1, Point p2) {
    return p1.x < p2.x;
}
double dist(Point a, Point b) {
    if (a.type == b.type) {
        return INF;
    }
    double dx = a.x - b.x;
    double dy = a.y - b.y;
    return sqrt(dx * dx + dy * dy);
}
double dfs(int l, int r) {
    if (l >= r) {
        return INF;
    }
    int mid = (l + r) / 2;
    double mid_x = points[mid].x;
    double res = min(dfs(l, mid), dfs(mid + 1, r));
    {
        int k = 0, i = l, j = mid + 1;
        while (i <= mid && j <= r) {
            if (points[i].y <= points[j].y) {
                temp[k++] = points[i++];
            } else {
                temp[k++] = points[j++];
            }
        }
        while (i <= mid) {
            temp[k++] = points[i++];
        }
        while (j <= r) {
            temp[k++] = points[j++];
        }
        for (i = 0, j = l; i < k; i++, j++) {
            points[j] = temp[i];
        }
    }
    int k = 0;
    for (int i = l; i <= r; i++) {
        if (points[i].x >= mid_x - res && points[i].x <= mid_x + res) {
            temp[k++] = points[i];
        }
    }
    for (int i = 0; i < k; i++) {
        for (int j = i - 1; j >= 0 && temp[i].y - temp[j].y <= res; j--) {
            res = min(res, dist(temp[i], temp[j]));
        }
    }
    return res;
}
int main() {
    int T;
    cin >> T;
    while (T--) {
        int n;
        cin >> n;
        for (int i = 0; i < n; i++) {
            cin >> points[i].x >> points[i].y;
            points[i].type = 0;
        }
        for (int i = n; i < n * 2; i++) {
            cin >> points[i].x >> points[i].y;
            points[i].type = 1;
        }
        sort(points, points + n * 2, cmp);
        cout << fixed << setprecision(3) << dfs(0, n * 2 - 1) << endl;
    }
    return 0;
}