結果

問題 No.94 圏外です。(EASY)
ユーザー tu-satu-sa
提出日時 2018-06-23 06:25:17
言語 C++14
(gcc 12.3.0 + boost 1.83.0)
結果
CE  
(最新)
AC  
(最初)
実行時間 -
コード長 9,481 bytes
コンパイル時間 1,102 ms
コンパイル使用メモリ 128,600 KB
最終ジャッジ日時 2024-04-27 02:34:22
合計ジャッジ時間 1,541 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge2
このコードへのチャレンジ
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コンパイルエラー時のメッセージ・ソースコードは、提出者また管理者しか表示できないようにしております。（リジャッジ後のコンパイルエラーは公開されます）
ただし、clay言語の場合は開発者のデバッグのため、公開されます。

コンパイルメッセージ
main.cpp: In function 'std::ostream& operator<<(std::ostream&, const iter_pair_t<T>&)':
main.cpp:78:33: error: 'ostream_iterator' was not declared in this scope
   78 |         std::copy(v.beg, v.end, ostream_iterator<typename decltype(v.beg)::reference>(out, " "));
      |                                 ^~~~~~~~~~~~~~~~
main.cpp:28:1: note: 'std::ostream_iterator' is defined in header '<iterator>'; did you forget to '#include <iterator>'?
   27 | #include <mutex>
  +++ |+#include <iterator>
   28 | using namespace std;
main.cpp:78:85: error: expected '(' before '>' token
   78 |         std::copy(v.beg, v.end, ostream_iterator<typename decltype(v.beg)::reference>(out, " "));
      |                                                                                     ^
      |                                                                                     (

ソースコード

diff # 

////////////////////////////////////////
///  tu3 pro-con template            ///
////////////////////////////////////////
#include <cassert>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <algorithm>
#include <numeric>
#include <functional>
#include <vector>
#include <queue>
#include <string>
#include <complex>
#include <stack>
#include <set>
#include <map>
#include <list>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <regex>
#include <type_traits>
#include <mutex>
using namespace std;

//// MACRO ////
#define countof(a) (sizeof(a)/sizeof(a[0]))

#define REP(i,n) for (int i = 0; i < (n); i++)
#define RREP(i,n) for (int i = (n)-1; i >= 0; i--)
#define FOR(i,s,n) for (int i = (s); i < (n); i++)
#define RFOR(i,s,n) for (int i = (n)-1; i >= (s); i--)
#define pos(c,i) c.being() + (i)
#define allof(c) c.begin(), c.end()
#define aallof(a) a, countof(a)
#define partof(c,i,n) c.begin() + (i), c.begin() + (i) + (n)
#define apartof(a,i,n) a + (i), a + (i) + (n)
#define long long long

#define EPS 1e-9
#define INF (1L << 28)
#define LINF (1LL << 60)

#define PREDICATE(t,a,exp) [&](const t & a) -> bool { return exp; }
#define COMPARISON_T(t) bool(*)(const t &, const t &)
#define COMPARISON(t,a,b,exp) [&](const t & a, const t & b) -> bool { return exp; }
#define CONVERTER(TSrc,t,TDest,exp) [&](const TSrc &t)->TDest { return exp; }

inline int sign_of(double x) { return (abs(x) < EPS ? 0 : x > 0 ? 1 : -1); }
inline bool inRange(int val, int min, int max) { return val >= min && val < max; }
inline bool inRange(double val, double min, double max) { return val - min > -EPS && val - max < EPS; }
inline bool inRange(int x, int y, int W, int H) { return x >= 0 && x < W && y >= 0 && y < H; } // W,H含まない

template <class T> struct vevector : public vector<vector<T>> { vevector(int n = 0, int m = 0, const T &initial = T()) : vector<vector<T>>(n, vector<T>(m, initial)) { } };
template <class T> struct vevevector : public vector<vevector<T>> { vevevector(int n = 0, int m = 0, int l = 0, const T &initial = T()) : vector<vevector<T>>(n, vevector<T>(m, l, initial)) { } };
template <class T> struct vevevevector : public vector<vevevector<T>> { vevevevector(int n = 0, int m = 0, int l = 0, int k = 0, const T &initial = T()) : vector<vevevector<T>>(n, vevevector<T>(m, l, k, initial)) { } };

//// i/o helper ////

namespace std {
template <class T1, class T2> inline istream & operator >> (istream & in, pair<T1, T2> &p) { in >> p.first >> p.second; return in; }
template <class T1, class T2> inline ostream & operator << (ostream &out, const pair<T1, T2> &p) { out << p.first << " " << p.second; return out; }
}
template <class T> T read() { T t; cin >> t; return t; }
template <class T> vector<T> read(int n) { vector<T> v; REP(i, n) { v.push_back(read<T>()); } return v; }
template <class T> vevector<T> read(int n, int m) { vevector<T> v; REP(i, n) v.push_back(read<T>(m)); return v; }
template <class T> vector<T> readjag() { return read<T>(read<int>()); }
template <class T> vevector<T> readjag(int n) { vevector<T> v; REP(i, n) v.push_back(readjag<T>()); return v; }

template <class T> struct iter_pair_t { T beg, end; };
template <class T> iter_pair_t<T> iter_pair(T beg, T end) { return iter_pair_t<T>{beg, end}; }
template <class T> ostream & operator << (ostream &out, const iter_pair_t<T> &v)
{
	std::copy(v.beg, v.end, ostream_iterator<typename decltype(v.beg)::reference>(out, " "));
	return out;
}
template <class T1> ostream & operator << (ostream &out, const vector<T1> &v) { return out << iter_pair(begin(v), end(v)); }
template <class T1> ostream & operator << (ostream &out, const set<T1> &v) { return out << iter_pair(begin(v), end(v)); }
template <class T1, class T2> ostream & operator << (ostream &out, const map<T1,T2> &v) { return out << iter_pair(begin(v), end(v)); }

struct _Reader { istream &cin;template <class T> _Reader operator ,(T &rhs) { cin >> rhs; return *this; } };
struct _Writer { ostream &cout; bool f{false	}; template <class T> _Writer operator ,(const T &rhs) { cout << (f ? " " : "") << rhs; f = true; return *this; } };
#define READ(t,...) t __VA_ARGS__; (_Reader{cin}), __VA_ARGS__
#define WRITE(...) (_Writer{cout}), __VA_ARGS__; cout << endl
#define DEBUG(...) (_Writer{cerr}), __VA_ARGS__; cerr << endl

void solve();
int main()
{
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	cout << setprecision(std::numeric_limits<double>::max_digits10);
	solve();
	
	return 0;
}

// 平面上の点。もしくは平面上のベクトル。
struct P2
{
	double x, y;
	P2(double x = 0, double y = 0) : x(x), y(y) { }
	P2(complex<double> c) : x(c.real()), y(c.imag()) { }
	P2 operator +() const { return *this; }
	P2 operator +(const P2 &_) const { return P2(x + _.x, y + _.y); }
	P2 operator -() const { return P2(-x, -y); }
	P2 operator -(const P2 &_) const { return *this + -_; }
	P2 operator *(double _) const { return P2(x*_, y*_); }
	P2 operator /(double _) const { return P2(x / _, y / _); }
	double dot(const P2 &_) const { return x * _.x + y * _.y; } // 内積
	double cross(const P2 &_) const { return x * _.y - y * _.x; } // 外積
	double sqlength() const { return dot(*this); } // 二乗長さ
	double length() const { return sqrt(sqlength()); } // 長さ
	P2 orthogonal() const { return P2(y, -x); }
	P2 direction() const { return *this / length(); } // 方向ベクトル
	double arg() const { return atan2(y, x); }
	static P2 polar(double length, double theta) { return P2(std::polar(length, theta)); }
};
inline istream & operator>>(istream & in, P2 & p) { in >> p.x >> p.y; return in; }
inline ostream & operator<<(ostream & out, const P2 & p) { out << p.x << ' ' << p.y; return out; }
inline double abs(P2 p2) { return p2.length(); } // 長さ
inline P2 orthogonal(P2 p) { return p.orthogonal(); } // 垂直
inline complex<double> orthogonal(complex<double> c) { return  c * complex<double>(0, 1); } // 垂直

/// 点集合の凸包 O(n log n)
typedef int Index;
vector<Index> convex_hull(const vector<P2> &points)
{
	int N = points.size();
	if (N == 0) { return { }; }
	if (N == 1) { return { 0 }; }
	if (N == 2) { return { 0,1 }; }

	vector<Index> pidx(N);
	REP(i, N) { pidx[i] = i; }

	auto cmpP2 = COMPARISON(P2, a, b, a.x != b.x ? a.x < b.x : a.y < b.y);
	sort(allof(pidx), COMPARISON(Index, a, b, cmpP2(points[a], points[b])));

	vector<Index> ret;
	ret.reserve(N * 2);

	auto cw = [](P2 a, P2 b, P2 c) { return (b - a).cross(c - a) > EPS; };
	auto f = [&](int K, int i)
	{
		while (ret.size() > K)
		{
			P2 a = points[ret[ret.size() - 2]];
			P2 b = points[ret[ret.size() - 1]];
			P2 c = points[pidx[i]];
			if (cw(a, b, c)) { break; }
			ret.pop_back();
		}
		ret.push_back(pidx[i]);
	};

	REP(i, N) { f(1, i); }
	int K = ret.size();
	RREP(i, N - 1) { f(K, i); }
	ret.pop_back();
	return ret;
}


/// convex_hull + キャリパー法。O(n long n) + O(n)
// 点集合のうち一番遠いペアの距離
pair<int,int> convex_diameter(const vector<P2> &points)
{
	vector<Index> vi = convex_hull(points);
	int N = vi.size();
	
	vector<P2> p(N);
	REP(i, N) { p[i] = points[vi[i]]; }

	if (N == 0) { return { 0,0 }; }
	if (N == 1) { return { vi[0], vi[0] }; }
	if (N == 2) { return { vi[0], vi[1] }; }

	int si = 0, sj = 0;
	auto cmpP2 = COMPARISON(P2, a, b, a.x != b.x ? a.x < b.x : a.y < b.y);
	REP(k, N)
	{
		if (cmpP2(p[k], p[si])) { si = k; }
		if (cmpP2(p[sj], p[k])) { sj = k; }
	}

	int i = si, j = sj;
	int maxI = 0, maxJ = 0;
	double maxD = -INF;

	do
	{
		double d = (p[i] - p[j]).sqlength();
		if (d > maxD)
		{
			maxD = d;
			maxI = i;
			maxJ = j;
		}

		int ni = (i + 1) % N;
		int nj = (j + 1) % N;

		if ((p[ni] - p[i]).cross(p[nj] - p[j]) >= 0)
		{
			j = nj;
		}
		else
		{
			i = ni;
		}
	} while (i != si || j != sj);

	return { vi[maxI], vi[maxJ] };
}

/// ユニオンファインド森。ユニオンファインドが必要な問題が解ける。
struct UnionFindForest
{
	vector<int> p;
	UnionFindForest(int n) : p(n, -1) { }
	int rootOf(int i) { return p[i] < 0 ? i : (p[i] = rootOf(p[i])); }
	int countOf(int i) { return -p[rootOf(i)]; }

	bool linked(int a, int b) { return rootOf(a) == rootOf(b); }
	bool link(int a, int b)
	{
		int x = rootOf(a), y = rootOf(b);
		if (x != y)
		{
			p[x] += p[y];
			p[y] = x;
		}
		return x != y;
	}
};

////////////////////
/// template end ///
////////////////////

void solve()
{
	READ(int, N);
	auto X = read<P2>(N);
	
	if (N == 0) { WRITE(1); return; }

	sort(allof(X), COMPARISON(P2, a, b, a.x != b.x ? a.x < b.x : a.y < b.y));

	int H = 2001, W = 2001;
	vevevector<int> buckets(W, H);

	REP(i, N)
	{
		P2 p = X[i];
		int x = (p.x + 10000) / 10 + EPS;
		int y = (p.y + 10000) / 10 + EPS;
		buckets[x][y].push_back(i);
	}

	UnionFindForest g(N);
	int dx[] = { -1,0,1,-1,0,1,-1,0,1 };
	int dy[] = { -1,-1,-1,0,0,0,1,1,1 };

	REP(x, W)
	{
		REP(y, H)
		{
			for(int i : buckets[x][y])
			{
				REP(k, 9)
				{
					int xx = x + dx[k];
					int yy = y + dy[k];
					if (inRange(xx, yy, W, H))
					{
						for (int j : buckets[xx][yy])
						{
							if ((X[i] - X[j]).sqlength() <= 100)
							{
								g.link(i, j);
							}
						}
					}
				}
			}
		}
	}

	map<int, vector<P2>> S;
	REP(i, N)
	{
		S[g.rootOf(i)].push_back(X[i]);
	}

	double ans = 0;
	for(auto &p : S)
	{
		auto &v = p.second;
		auto pi = convex_diameter(v);
		auto d = (v[pi.first] - v[pi.second]).length();
		ans = max(ans, d);
	}
	WRITE(ans + 2);
}
0