1 #include <set> 2 #include <map> 3 #include <list> 4 #include <cmath> 5 #include <queue> 6 #include <vector> 7 #include <bitset> 8 #include <string> 9 #include <cctype>10 #include <cstdio>11 #include <cstring>12 #include <cstdlib>13 #include <iostream>14 #include <algorithm>15 16 using namespace std;17 18 typedef long long ll;19 typedef unsigned long long ull;20 #define inf (0x3f3f3f3f)21 #define lnf (0x3f3f3f3f3f3f3f3f)22 #define eps (1e-8)23 int sgn(double a) {return a < -eps ? -1 : a < eps ? 0 : 1;}24 25 //--------------------------26 27 28 int t;29 int m, n;30 31 class point {32 public:33     double x, y;34     point(double x, double y) {35         this->x = x;36         this->y = y;37     }38 39 };40 41 vector<point> p;42 43 double dis(point p1, point p2) {44     return sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));45 }46 47 void solve() {48     scanf("%d", &t);49     while (t--) {50         p.clear();51         scanf("%d%d", &m, &n);52         for (int i = 0; i < m; i++) {53             double x, y;54             scanf("%lf%lf", &x, &y);55             p.push_back(point(x, y));56         }57         int ans = inf;58         for (int i = 0; i < m; i++) {59             double res;60             double ds[110];61             for (int j = 0; j < m; j++) {62                 ds[j] = dis(p[i], p[j]);63             }64             sort(ds, ds + m);65             res = ceil(ds[n - 1]);66             if (res == ds[n - 1])res += 1;67             if (m > n && res >= ds[n])continue;68             ans = min(ans, (int)res);69         }70         if (ans == inf || n > m) {71             puts("-1");72         } else {73             printf("%d\n", ans);74         }75     }76 77 }78 79 int main() {80 81 #ifndef ONLINE_JUDGE82     freopen("1.in", "r", stdin);83     //freopen("1.out", "w", stdout);84 #endif85     //iostream::sync_with_stdio(false);86     solve();87     return 0;88 }