Language: C++

#define N 300005
#define inf 2000000000
#define EPS 1e-6
#define MOD (ll)1e15
#define __builtin_popcount(x) __popcnt(x)
 
using namespace std;
 
typedef long long ll;
typedef pair<double, double> pr;
typedef pair<pair<int, int>, int> tup;
 
double find_r(double x, double y, vector<pr> &p)
{
	double l = 0, r = 1000;
	while (abs(r - l) > 1e-7) {
		double m = (l + r) / 2;
 
		bool ok = 1;
		fore(i, 0, p.size())
		{
			if ((x - p[i].first) * (x - p[i].first) + (y - p[i].second) * (y - p[i].second) - m * m > 0)
				ok = 0;
		}
 
		if (ok)
			r = m;
		else
			l = m;
	}
 
	return r;
}
 
double find_x(double y, vector<pr> &p)
{
	double l = 0, r = 1000;
	while (r - l > EPS) {
		double m1 = l + (r - l) / 3,
			m2 = r - (r - l) / 3;
		if (find_r(m1, y, p) > find_r(m2, y, p))
			l = m1;
		else
			r = m2;
	}
	return r;
}
 
inline void solve()
{
	int n;
	cin >> n;
	vector<pr> v(n);
	fore(i, 0, n)
		cin >> v[i].first >> v[i].second;
 
	double mn = 1e18;
	double y = 0;
	double l = 0, r = 1000;
 
	for (double x = l; x <= r; x += 0.2)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
	for (double x = y - 0.1; x <= y + 0.1; x += 0.002)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
	for (double x = y - 0.001; x <= y + 0.001; x += 0.0002)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
	for (double x = y - 0.0001; x <= y + 0.0001; x += 0.00002)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
	for (double x = y - 0.00001; x <= y + 0.00001; x += 0.000002)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
	for (double x = y - 0.000001; x <= y + 0.000001; x += 0.0000002)
	{
		double rr = find_r(find_x(x, v), x, v);
		if (rr < mn)
		{
			mn = rr;
			y = x;
		}
	}
 
	cout << fixed << setprecision(6) << mn;
}
 
int main()
{
	fast;
#if defined(_DEBUG)
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	solve();
}

Compiler output:
a.cc:10:9: error: 'pair' does not name a type
   10 | typedef pair<double, double> pr;
      |         ^~~~
a.cc:11:9: error: 'pair' does not name a type
   11 | typedef pair<pair<int, int>, int> tup;
      |         ^~~~
a.cc:13:35: error: 'vector' has not been declared
   13 | double find_r(double x, double y, vector<pr> &p)
      |                                   ^~~~~~
a.cc:13:41: error: expected ',' or '...' before '<' token
   13 | double find_r(double x, double y, vector<pr> &p)
      |                                         ^
a.cc: In function 'double find_r(double, double, int)':
a.cc:16:16: error: 'abs' was not declared in this scope
   16 |         while (abs(r - l) > 1e-7) {
      |                ^~~
a.cc:20:22: error: 'i' was not declared in this scope
   20 |                 fore(i, 0, p.size())
      |                      ^
a.cc:20:28: error: 'p' was not declared in this scope
   20 |                 fore(i, 0, p.size())
      |                            ^
a.cc:20:17: error: 'fore' was not declared in this scope
   20 |                 fore(i, 0, p.size())
      |                 ^~~~
a.cc: At global scope:
a.cc:35:25: error: 'vector' has not been declared
   35 | double find_x(double y, vector<pr> &p)
      |                         ^~~~~~
a.cc:35:31: error: expected ',' or '...' before '<' token
   35 | double find_x(double y, vector<pr> &p)
      |                               ^
a.cc: In function 'double find_x(double, int)':
a.cc:41:35: error: 'p' was not declared in this scope
   41 |                 if (find_r(m1, y, p) > find_r(m2, y, p))
      |                                   ^
a.cc: In function 'void solve()':
a.cc:52:9: error: 'cin' was not declared in this scope
   52 |         cin >> n;
      |         ^~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | #define N 300005
a.cc:53:9: error: 'vector' was not declared in this scope
   53 |         vector<pr> v(n);
      |         ^~~~~~
a.cc:1:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
  +++ |+#include <vector>
    1 | #define N 300005
a.cc:53:16: error: 'pr' was not declared in this scope
   53 |         vector<pr> v(n);
      |                ^~
a.cc:53:20: error: 'v' was not declared in this scope
   53 |         vector<pr> v(n);
      |                    ^
a.cc:54:14: error: 'i' was not declared in this scope
   54 |         fore(i, 0, n)
      |              ^
a.cc:54:9: error: 'fore' was not declared in this scope
   54 |         fore(i, 0, n)
      |         ^~~~
a.cc:116:9: error: 'cout' was not declared in this scope
  116 |         cout << fixed << setprecision(6) << mn;
      |         ^~~~
a.cc:116:9: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:116:17: error: 'fixed' was not declared in this scope
  116 |         cout << fixed << setprecision(6) << mn;
      |                 ^~~~~
a.cc:1:1: note: 'std::fixed' is defined in header '<ios>'; this is probably fixable by adding '#include <ios>'
  +++ |+#include <ios>
    1 | #define N 300005
a.cc:116:26: error: 'setprecision' was not declared in this scope
  116 |         cout << fixed << setprecision(6) << mn;
      |                          ^~~~~~~~~~~~
a.cc:1:1: note: 'std::setprecision' is defined in header '<iomanip>'; this is probably fixable by adding '#include <iomanip>'
  +++ |+#include <iomanip>
    1 | #define N 300005
a.cc: In function 'int main()':
a.cc:121:9: error: 'fast' was not declared in this scope
  121 |         fast;
      |         ^~~~