Add 30315.cpp

30xxx/30315.cpp

@@ -0,0 +1,30 @@
+#include <algorithm>
+#include <cmath>
+#include <iomanip>
+#include <iostream>
+#include <vector>
+using namespace std;
+
+void solve(void) {
+  int k; cin >> k;
+  vector<int> x(k), y(k);
+  for (int i=0; i<k; i++) cin >> x[i] >> y[i];
+
+  double ans = 1e9;
+  for (int i=0; i<k; i++) {
+    double sum = 0;
+    for (int j=0; j<k; j++) {
+      sum += hypot(x[i]-x[j], y[i]-y[j]);
+    }
+    ans = min(ans, sum / (k-1));
+  }
+  cout << fixed << setprecision(7) << ans;
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  solve();
+  return 0;
+}