oj.uz

Submission #242190

# Submission time Handle Problem Language Result Execution time Memory
242190 2020-06-27T05:21:46 Z arnold518 None (KOI18_footprint) C++14
14 / 100
 1002 ms 134236 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 3000;
const ll INF = 1e9;

struct Point { ll x, y; };
bool operator == (const Point &p, const Point &q) { return p.x==q.x && p.y==q.y; }
Point operator + (const Point &p, const Point &q) { return {p.x+q.x, p.y+q.y}; }
Point operator - (const Point &p, const Point &q) { return {p.x-q.x, p.y-q.y}; }

ll ccw(Point p, Point q) { return p.x*q.y-p.y*q.x; }
ll ccw(Point p, Point q1, Point q2) { return ccw(q1-p, q2-p); }

int N;
Point A[MAXN+10], P={INF, INF};

pii dp1[MAXN+10][MAXN+10], dp2[MAXN+10][MAXN+10];
pair<int, pii> ans;

int main()
{
	int i, j, k;

	scanf("%d", &N);
	for(i=1; i<=N; i++) scanf("%lld%lld", &A[i].x, &A[i].y);
	for(i=1; i<=N; i++) if(A[i].y<P.y) P=A[i];
	for(i=1; i<=N; i++) if(A[i]==P) break;
	for(; i<N; i++) swap(A[i], A[i+1]);

	N--;
	sort(A+1, A+N+1, [&](const Point &p, const Point &q) { return ccw(P, p, q)<0; });

	for(i=1; i<=N; i++)
	{
		vector<int> L, R;
		for(j=i+1; j<=N; j++) R.push_back(j), dp1[j][i+1]=dp2[j][i+1]={-987654321, 0};
		for(j=1; j<i; j++) L.push_back(j);

		sort(L.begin(), L.end(), [&](const int &p, const int &q) { return ccw(A[i]-A[p], A[i]-A[q])<0; });
		sort(R.begin(), R.end(), [&](const int &p, const int &q) { return ccw(A[p]-A[i], A[q]-A[i])<0; });

		pii now={2, i};
		for(j=0, k=0; j<R.size(); j++)
		{
			for(; k<L.size() && ccw(A[i]-A[L[k]], A[R[j]]-A[i])<=0; k++) now=max(now, {dp2[L[k]][i].first+1, L[k]});
			dp1[i][R[j]]=max(dp1[i][R[j]], now);
		}

		now={-987654321, 0};
		for(j=R.size()-1, k=L.size()-1; j>=0; j--)
		{
			for(; k>=0 && ccw(A[i]-A[L[k]], A[R[j]]-A[i])>=0; k--) now=max(now, {dp1[L[k]][i].first+1, L[k]});
			dp2[i][R[j]]=max(dp2[i][R[j]], now);
			ans=max(ans, {dp2[i][R[j]].first, {i, R[j]}});
		}
	}
	if(ans.first==0) return !printf("0\n");
	vector<Point> V;
	pii v=ans.second; int t=2;
	V.push_back(P);
	while(1)
	{
		V.push_back(A[v.second]);
		if(v.first==v.second) break;
		if(t==2)
		{
			v={dp2[v.first][v.second].second, v.first};
			t=1;
		}
		else
		{
			v={dp1[v.first][v.second].second, v.first};
			t=2;
		}
	}

	printf("%d\n", V.size());
	for(auto it : V) printf("%lld %lld\n", it.x, it.y);
}

Compilation message

footprint.cpp: In function 'int main()':
footprint.cpp:48:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0, k=0; j<R.size(); j++)
                 ~^~~~~~~~~
footprint.cpp:50:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(; k<L.size() && ccw(A[i]-A[L[k]], A[R[j]]-A[i])<=0; k++) now=max(now, {dp2[L[k]][i].first+1, L[k]});
          ~^~~~~~~~~
footprint.cpp:82:25: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<Point>::size_type {aka long unsigned int}' [-Wformat=]
  printf("%d\n", V.size());
                 ~~~~~~~~^
footprint.cpp:29:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
footprint.cpp:30:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(i=1; i<=N; i++) scanf("%lld%lld", &A[i].x, &A[i].y);
                      ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 924 ms 129500 KB Output is correct
2 Correct 1000 ms 131832 KB Output is correct
3 Correct 958 ms 130552 KB Output is correct
4 Correct 978 ms 131884 KB Output is correct
5 Correct 984 ms 131272 KB Output is correct
6 Correct 983 ms 132044 KB Output is correct
7 Correct 958 ms 131576 KB Output is correct
8 Correct 987 ms 132164 KB Output is correct
9 Correct 992 ms 132580 KB Output is correct
10 Correct 987 ms 132216 KB Output is correct
11 Correct 991 ms 132032 KB Output is correct
12 Correct 999 ms 132704 KB Output is correct
13 Correct 1002 ms 134236 KB Output is correct
14 Correct 989 ms 132088 KB Output is correct
15 Correct 965 ms 130680 KB Output is correct

Subtask #2
0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 4 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Incorrect 5 ms 384 KB Output isn't correct
8 Halted 0 ms 0 KB -

Subtask #3
0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 4 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Incorrect 5 ms 384 KB Output isn't correct
8 Halted 0 ms 0 KB -

Subtask #4
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 924 ms 129500 KB Output is correct
2 Correct 1000 ms 131832 KB Output is correct
3 Correct 958 ms 130552 KB Output is correct
4 Correct 978 ms 131884 KB Output is correct
5 Correct 984 ms 131272 KB Output is correct
6 Correct 983 ms 132044 KB Output is correct
7 Correct 958 ms 131576 KB Output is correct
8 Correct 987 ms 132164 KB Output is correct
9 Correct 992 ms 132580 KB Output is correct
10 Correct 987 ms 132216 KB Output is correct
11 Correct 991 ms 132032 KB Output is correct
12 Correct 999 ms 132704 KB Output is correct
13 Correct 1002 ms 134236 KB Output is correct
14 Correct 989 ms 132088 KB Output is correct
15 Correct 965 ms 130680 KB Output is correct
16 Correct 4 ms 384 KB Output is correct
17 Correct 4 ms 384 KB Output is correct
18 Correct 5 ms 384 KB Output is correct
19 Correct 4 ms 384 KB Output is correct
20 Correct 5 ms 384 KB Output is correct
21 Correct 5 ms 384 KB Output is correct
22 Incorrect 5 ms 384 KB Output isn't correct
23 Halted 0 ms 0 KB -