Submission #6954033

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Source Code Expand

#include <bits/stdc++.h>

// Begin {{{
using namespace std;

#define all(x) x.begin(), x.end()
#define rep(i, n) for (i64 i = 0; i < (n); ++i)
#define reps(i, s, n) for (i64 i = (s); i <= (n); ++i)
#define VAR(Type, ...) Type __VA_ARGS__; IN(__VA_ARGS__)

using i64 = int_fast64_t;
using pii = pair<i64, i64>;

template<class A, class B>
inline bool chmax(A &a, const B &b) { return b > a && (a = b, true); }

template<class A, class B>
inline bool chmin(A &a, const B &b) { return b < a && (a = b, true); }

constexpr int INF = 0x3f3f3f3f;
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr int MOD = int(1e9) + 7;

//IN
void IN() {}
template<class Head, class... Tail>
void IN(Head&& head, Tail&&... tail) {
  cin >> head;
  IN(forward<Tail>(tail)...);
}

//OUTS
template<size_t> struct int_{};
template<class Tuple, size_t Pos>
ostream& print_tuple(ostream& out, const Tuple& t, int_<Pos>) {
  out << get<tuple_size<Tuple>::value-Pos>(t) << " ";
  return print_tuple(out, t, int_<Pos-1>());
}

template <class Tuple>
ostream& print_tuple(ostream& out, const Tuple& t, int_<1>) {
  return out << get<tuple_size<Tuple>::value-1>(t);
}

template<class... Args>
ostream& operator<<(ostream& out, const tuple<Args...>& t) {
  return print_tuple(out, t, int_<sizeof...(Args)>());
}

#define OUTS(...) cout << make_tuple(__VA_ARGS__) << "\n";

//OUTL
void OUTL() {}
template<class Head, class... Tail>
void OUTL(Head&& head, Tail&&... tail) {
  cout << head << "\n";
  OUTL(forward<Tail>(tail)...);
}
// }}} End

using ld = long double;

signed main()
{
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  VAR(int, r, n, m);

  ld res = 0.0;
  ld range = ((ld)r * 2.0) / (ld)n;
  ld j = range;
  reps(i, 1, n+m-1) {
    ld y = fabs((ld)r - j);
    ld _y = fabs((ld)r - (j - (range * (ld)m)));
    ld x = sqrt((ld)r*r - y*y) * 2.0;
    ld _x = sqrt((ld)r*r - _y*_y) * 2.0;
    res += fmax(x, _x);
    j += range;
  }

  cout << fixed << setprecision(20) << res << "\n";

  return 0;
}

Submission Info

Judge Result