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Submission #284848

# Submission time Handle Problem Language Result Execution time Memory
284848 2020-08-28T06:49:16 Z youngyojun None (KOI18_footprint) C++17
41 / 100
 2000 ms 162708 KB 
#include <bits/stdc++.h>
#define eb emplace_back
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
ll operator * (const pll &a, const pll &b) { return a.fi * b.se - b.fi * a.se; }
ll ccw(const pll &a, const pll &b, const pll &c) { return a*b + b*c + c*a; }

ll MP[3005][3005];
inline ll ccw(int a, int b, int c) { return MP[a][b] + MP[b][c] - MP[a][c]; }

int D[3005][3005], RD[3005][3005];
int E[3005][3005], RE[3005][3005];

int NV[3005], NVn;
int PV[3005], PVn;

pll P[3005];

int N;

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);

	cin >> N;
	for(int i = 0; i < N; i++) {
		cin >> P[i].fi >> P[i].se;
		if(P[i].se < P[0].se) swap(P[0], P[i]);
	}
	N--;
	sort(P+1, P+N+1, [&](const pll &a, const pll &b) { return ccw(P[0], a, b) > 0; });

	for(int i = 1; i <= N; i++) for(int j = 0; j < i; j++) {
		MP[i][j] = P[i] * P[j];
		MP[j][i] = -MP[i][j];
	}

	for(int i = 1; i <= N; i++) {
		D[i][0] = 2;

		NVn = PVn = 0;
	{
		int k = i+1;
		for(; k <= N && !ccw(0, i, k); k++);
		for(; k <= N; k++) NV[NVn++] = k;
	}
	{
		PV[PVn++] = 0;
		int j = i-1;
		for(; j && !ccw(0, i, j); j--);
		for(; j; j--) PV[PVn++] = j;
	}
		sort(NV, NV+NVn, [&](int a, int b) { return ccw(i, a, b) > 0; });
		sort(PV, PV+PVn, [&](int a, int b) { return ccw(i, a, b) > 0; });

		for(int ki = 0, k, ji = 0, j, mx = 0, mxj; ki < NVn; ki++) {
			k = NV[ki];
			for(; ji < PVn; ji++) {
				j = PV[ji];
				if(ccw(j, i, k) <= 0) break;
				if(mx < D[i][j]) {
					mx = D[i][j];
					mxj = j;
				}
			}
			if(mx) {
				E[k][i] = mx + 1;
				RE[k][i] = mxj;
			}
		}

		for(int ki = NVn-1, k, ji = PVn-1, j, mx = 0, mxj; 0 <= ki; ki--) {
			k = NV[ki];
			for(; 0 <= ji; ji--) {
				j = PV[ji];
				if(ccw(j, i, k) >= 0) break;
				if(mx < E[i][j]) {
					mx = E[i][j];
					mxj = j;
				}
			}
			if(mx) {
				D[k][i] = mx + 1;
				RD[k][i] = mxj;
			}
		}
	}

{
	int Ans = 0, I, J;
	for(int i = N; i; i--) for(int j = i-1; j; j--)
		if(Ans < D[i][j]) {
			Ans = D[i][j];
			I = i; J = j;
		}
	
	if(Ans < 4) { puts("0"); exit(0); }
	cout << Ans << '\n';

	vector<int> V;
	for(int t = 0; 2 < Ans; Ans--, t ^= 1) {
		V.eb(I);
		I = (t ? RE : RD)[I][J];
		swap(I, J);
	}
	V.eb(I); V.eb(J);

	reverse(V.begin(), V.end());
	for(int v : V) cout << P[v].fi << ' ' << P[v].se << '\n';
}
	return 0;
}

Subtask #1
0 / 14.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2104 ms 162708 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #2
12.0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 1 ms 384 KB Output is correct
3 Correct 1 ms 384 KB Output is correct
4 Correct 1 ms 512 KB Output is correct
5 Correct 1 ms 512 KB Output is correct
6 Correct 1 ms 544 KB Output is correct
7 Correct 1 ms 512 KB Output is correct
8 Correct 1 ms 512 KB Output is correct
9 Correct 1 ms 512 KB Output is correct
10 Correct 1 ms 512 KB Output is correct
11 Correct 0 ms 512 KB Output is correct
12 Correct 0 ms 512 KB Output is correct
13 Correct 1 ms 512 KB Output is correct
14 Correct 1 ms 512 KB Output is correct
15 Correct 1 ms 512 KB Output is correct
16 Correct 1 ms 512 KB Output is correct
17 Correct 0 ms 512 KB Output is correct
18 Correct 1 ms 512 KB Output is correct
19 Correct 0 ms 512 KB Output is correct
20 Correct 1 ms 512 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 384 KB Output is correct
2 Correct 1 ms 384 KB Output is correct
3 Correct 1 ms 384 KB Output is correct
4 Correct 1 ms 512 KB Output is correct
5 Correct 1 ms 512 KB Output is correct
6 Correct 1 ms 544 KB Output is correct
7 Correct 1 ms 512 KB Output is correct
8 Correct 1 ms 512 KB Output is correct
9 Correct 1 ms 512 KB Output is correct
10 Correct 1 ms 512 KB Output is correct
11 Correct 0 ms 512 KB Output is correct
12 Correct 0 ms 512 KB Output is correct
13 Correct 1 ms 512 KB Output is correct
14 Correct 1 ms 512 KB Output is correct
15 Correct 1 ms 512 KB Output is correct
16 Correct 1 ms 512 KB Output is correct
17 Correct 0 ms 512 KB Output is correct
18 Correct 1 ms 512 KB Output is correct
19 Correct 0 ms 512 KB Output is correct
20 Correct 1 ms 512 KB Output is correct
21 Correct 11 ms 7040 KB Output is correct
22 Correct 11 ms 7168 KB Output is correct
23 Correct 11 ms 7168 KB Output is correct
24 Correct 13 ms 7808 KB Output is correct
25 Correct 13 ms 7808 KB Output is correct
26 Correct 13 ms 7808 KB Output is correct
27 Correct 12 ms 7680 KB Output is correct
28 Correct 12 ms 7680 KB Output is correct
29 Correct 13 ms 7680 KB Output is correct
30 Correct 13 ms 7808 KB Output is correct
31 Correct 13 ms 7808 KB Output is correct
32 Correct 15 ms 7808 KB Output is correct
33 Correct 8 ms 6272 KB Output is correct
34 Correct 7 ms 6272 KB Output is correct
35 Correct 7 ms 6272 KB Output is correct

Subtask #4
0 / 45.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2104 ms 162708 KB Time limit exceeded
2 Halted 0 ms 0 KB -