oj.uz

Submission #242189

# Submission time Handle Problem Language Result Execution time Memory
242189 2020-06-27T05:20:49 Z arnold518 None (KOI18_footprint) C++14
14 / 100
 1030 ms 134008 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;

	ans.first=-987654321;
	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==-987654321) 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;
		}
	}

	assert(V.size()==ans.first+1);
	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:49:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0, k=0; j<R.size(); j++)
                 ~^~~~~~~~~
footprint.cpp:51:11: 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]});
          ~^~~~~~~~~
In file included from /usr/include/c++/7/cassert:44:0,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:33,
                 from footprint.cpp:1:
footprint.cpp:83:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  assert(V.size()==ans.first+1);
         ~~~~~~~~^~~~~~~~~~~~~
footprint.cpp:84:25: 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:30:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
footprint.cpp:31:27: 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 937 ms 129348 KB Output is correct
2 Correct 993 ms 132088 KB Output is correct
3 Correct 971 ms 130632 KB Output is correct
4 Correct 975 ms 132088 KB Output is correct
5 Correct 962 ms 130936 KB Output is correct
6 Correct 1006 ms 131960 KB Output is correct
7 Correct 964 ms 131388 KB Output is correct
8 Correct 985 ms 132104 KB Output is correct
9 Correct 1022 ms 132344 KB Output is correct
10 Correct 989 ms 132216 KB Output is correct
11 Correct 1030 ms 132216 KB Output is correct
12 Correct 996 ms 132872 KB Output is correct
13 Correct 1022 ms 134008 KB Output is correct
14 Correct 993 ms 132088 KB Output is correct
15 Correct 972 ms 130936 KB Output is correct

Subtask #2
0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 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 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 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 937 ms 129348 KB Output is correct
2 Correct 993 ms 132088 KB Output is correct
3 Correct 971 ms 130632 KB Output is correct
4 Correct 975 ms 132088 KB Output is correct
5 Correct 962 ms 130936 KB Output is correct
6 Correct 1006 ms 131960 KB Output is correct
7 Correct 964 ms 131388 KB Output is correct
8 Correct 985 ms 132104 KB Output is correct
9 Correct 1022 ms 132344 KB Output is correct
10 Correct 989 ms 132216 KB Output is correct
11 Correct 1030 ms 132216 KB Output is correct
12 Correct 996 ms 132872 KB Output is correct
13 Correct 1022 ms 134008 KB Output is correct
14 Correct 993 ms 132088 KB Output is correct
15 Correct 972 ms 130936 KB Output is correct
16 Correct 5 ms 384 KB Output is correct
17 Correct 5 ms 384 KB Output is correct
18 Correct 5 ms 384 KB Output is correct
19 Correct 5 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 -