solution
最小球覆盖
code
/*Siberian Squirrel*/
/*Cute KiloFish*/
#include<bits/stdc++.h>
#define IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
using namespace std;
typedef long long ll;
const double PI = acos(-1);
const double eps = 1e-4;
const int INF = 0x3f3f3f3f;
/*const int MOD = 998244353, r = 119, k = 23, g = 3;
const int MOD = 1004535809, r = 479, k = 21, g = 3;*/
const int MOD = 1e9 + 7;
const int M = 1e7 + 10;
const int N = 2e5 + 10;
//inline int rnd(){static int seed=2333;return seed=(((seed*666666ll+20050818)%998244353)^1000000007)%1004535809;}
int n, pos;
struct node {
double x, y, z;
}p[N], _p;
double maxx = 0;
double dis(node a, node b) {
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)+(a.z-b.z)*(a.z-b.z));
}
void solve(double res = 1.0 * INF) {
double t = 10000.0;
while (t > eps) {
maxx = 0;
for (int i = 1; i <= n; ++ i) {
if (dis(_p, p[i]) > maxx) {
maxx = dis(_p, p[i]);
pos = i;
}
}
res = min(res, maxx);
_p.x += (p[pos].x - _p.x) * (t / 10000.0);
_p.y += (p[pos].y - _p.y) * (t / 10000.0);
_p.z += (p[pos].z - _p.z) * (t / 10000.0);
t *= 0.98;
}
cout << fixed << setprecision(19) << res << endl;;
}
signed main() {
IO;
#ifdef ACM_LOCAL
freopen("input", "r", stdin);
freopen("output", "w", stdout);
#endif
int o = 1, cases = 0;
// cin >> o;
while(o --) {
cin >> n;
for(int i=1; i<=n; ++i) {
cin >> p[i].x >> p[i].y >> p[i].z;
}
solve();
}
return 0;
}