oj.uz

Submission #242191

# Submission time Handle Problem Language Result Execution time Memory
242191 2020-06-27T05:22:37 Z arnold518 None (KOI18_footprint) C++14
14 / 100
 1008 ms 134136 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]}});
		}
	}
	assert(ans.first>0);
	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 917 ms 129400 KB Output is correct
2 Correct 993 ms 131832 KB Output is correct
3 Correct 956 ms 130424 KB Output is correct
4 Correct 968 ms 131832 KB Output is correct
5 Correct 949 ms 130936 KB Output is correct
6 Correct 976 ms 132088 KB Output is correct
7 Correct 960 ms 131320 KB Output is correct
8 Correct 967 ms 132216 KB Output is correct
9 Correct 961 ms 132472 KB Output is correct
10 Correct 974 ms 132192 KB Output is correct
11 Correct 968 ms 131960 KB Output is correct
12 Correct 967 ms 132600 KB Output is correct
13 Correct 1008 ms 134136 KB Output is correct
14 Correct 957 ms 132088 KB Output is correct
15 Correct 949 ms 130808 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 4 ms 384 KB Output is correct
3 Correct 4 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 4 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 4 ms 384 KB Output is correct
3 Correct 4 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 4 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 917 ms 129400 KB Output is correct
2 Correct 993 ms 131832 KB Output is correct
3 Correct 956 ms 130424 KB Output is correct
4 Correct 968 ms 131832 KB Output is correct
5 Correct 949 ms 130936 KB Output is correct
6 Correct 976 ms 132088 KB Output is correct
7 Correct 960 ms 131320 KB Output is correct
8 Correct 967 ms 132216 KB Output is correct
9 Correct 961 ms 132472 KB Output is correct
10 Correct 974 ms 132192 KB Output is correct
11 Correct 968 ms 131960 KB Output is correct
12 Correct 967 ms 132600 KB Output is correct
13 Correct 1008 ms 134136 KB Output is correct
14 Correct 957 ms 132088 KB Output is correct
15 Correct 949 ms 130808 KB Output is correct
16 Correct 5 ms 384 KB Output is correct
17 Correct 4 ms 384 KB Output is correct
18 Correct 4 ms 384 KB Output is correct
19 Correct 5 ms 384 KB Output is correct
20 Correct 4 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 -