BOJ 21335 - Another Eruption [C++]

문제

링크

풀이

#include <cmath>
#include <iomanip>
#include <iostream>
using namespace std;
 
void solve(void) {
  long long a; cin >> a;
 
  cout << fixed << setprecision(7) << 2 * sqrt(a) * sqrt(acos(-1));
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}