C++ :

#include<iostream>
#include<cstring>
#include<algorithm>
#include<algorithm>
#include<cmath>
#define INF 0x3f3f3f3f
using namespace std;
typedef long long int ll;
const int N = 2e5 + 10;
struct p{
    double x, y;
    int type;
}a[N], b[N];
bool cmp(p a, p b)
{
    if(a.x == b.x)
        return a.y < b.y;
    return a.x < b.x;
}
bool cmp1(p a, p b)
{
    if(a.y == b.y)
        return a.x < b.x;
    return a.y < b.y;
}
double dis(p a, p b)
{
    if(a.type == b.type)return INF;
    double x = a.x - b.x, y = a.y - b.y;
    return sqrt(x * x + y * y);
}
double solve(int l, int r)
{
    if(l == r)return INF;
    if(r - l == 1)
        return dis(a[l], a[r]);
    int mid = (l + r) >> 1;
    double ans = min(solve(l, mid), solve(mid + 1, r));
    int k = 0;
    for(int i = l; i <= r; i++)
        if(a[i].x >= a[mid].x - ans && a[i].x <= a[mid].x + ans)
            b[k++] = a[i];
    sort(b, b + k, cmp1);
    for(int i = 0; i < k; i++){
        for(int j = i + 1; j < k; j++){
            if(b[j].y >= b[i].y + ans)
                break;
            ans = min(ans, dis(a[i], a[j]));
        }
    }
    return ans;
}
int main()
{
    int t, n;
    cin >>t;
    while(t--){
        scanf("%d", &n);
        for(int i = 0; i < n; i++){
            scanf("%lf%lf", &a[i].x, &a[i].y);
            a[i].type = 0;
        }
        for(int i = n; i < 2 * n; i++){
            scanf("%lf%lf", &a[i].x, &a[i].y);
            a[i].type = 1;
        }
        n *= 2;
        sort(a, a + n, cmp);
        printf("%0.3f\n", solve(0, n - 1));
    }
    return 0;
}