Submission #64578

#	Time	Username	Problem	Language	Result	Execution time	Memory
64578		kjp4155	공룡 발자국 (KOI18_footprint)	C++17	100 / 100	1976 ms	190892 KiB

footprint

#include<bits/stdc++.h>
using namespace std;

#define VA_NUM_ARGS(...) VA_NUM_ARGS_IMPL_((0,__VA_ARGS__, 6,5,4,3,2,1))
#define VA_NUM_ARGS_IMPL_(tuple) VA_NUM_ARGS_IMPL tuple
#define VA_NUM_ARGS_IMPL(_0,_1,_2,_3,_4,_5,_6,N,...) N
#define macro_dispatcher(macro, ...) macro_dispatcher_(macro, VA_NUM_ARGS(__VA_ARGS__))
#define macro_dispatcher_(macro, nargs) macro_dispatcher__(macro, nargs)
#define macro_dispatcher__(macro, nargs) macro_dispatcher___(macro, nargs)
#define macro_dispatcher___(macro, nargs) macro ## nargs
#define Debug1(a)           cout<<#a<<"="<<(a)<<"\n"
#define Debug2(a,b)         cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<"\n"
#define Debug3(a,b,c)       cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<"\n"
#define Debug4(a,b,c,d)     cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<"\n"
#define Debug5(a,b,c,d,e)   cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<"\n"
#define Debug6(a,b,c,d,e,f) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<", "<<#f<<"="<<(f)<<"\n"
#define Debug(...) macro_dispatcher(Debug, __VA_ARGS__)(__VA_ARGS__)
#define DA(a,n) cout<<#a<<"=["; printarray(a,n); cout<<"]\n"
#define DAR(a,n,s) cout<<#a<<"["<<s<<"-"<<n-1<<"]=["; printarray(a,n,s); cout<<"]\n"

#define TT1 template<class T>
#define TT1T2 template<class T1, class T2>
#define TT1T2T3 template<class T1, class T2, class T3>
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v);
TT1T2 ostream& operator << (ostream& os, const pair<T1, T2>& p){ return os <<"("<<p.first<<", "<< p.second<<")"; }
TT1 ostream& operator << (ostream& os, const vector<T>& v){       bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v) {     bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const set<T1, T2>&v){    bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multiset<T1,T2>&v){bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2T3 ostream& operator << (ostream& os, const map<T1,T2,T3>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multimap<T1, T2>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, priority_queue<T1, T2> v) { bool f = 1; os << "["; while (!v.empty()) { auto x = v.top(); v.pop(); if (!f) os << ", "; f = 0; os << x; } return os << "]"; }
TT1T2 void printarray(const T1& a, T2 sz, T2 beg = 0){ for (T2 i = beg; i<sz; i++) cout << a[i] << " "; cout << endl; }

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;

#define Fi first
#define Se second
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define rep(i, n) for(int i=0;i<n;i++)
#define repp(i, n) for(int i=1;i<=n;i++)
#define all(x) x.begin(), x.end()
#define geti1(X) cin >> X
#define geti2(X,Y) cin >> X >> Y
#define geti3(X,Y,Z) cin >> X >> Y >> Z
#define geti4(X,Y,Z,W) cin >> X >> Y >> Z >> W
#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME
#define geti(...) GET_MACRO(__VA_ARGS__, geti4, geti3, geti2, geti1) (__VA_ARGS__)

#define INF 987654321

#define endl '\n'

const ll mod = 1e9 + 7;

const ll inf = 1e14;

/*
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <vector>
using namespace std;

typedef long long ll;
*/
// 계산을 편리하게 하기 위한 Point구조체 및 몇가지 연산자 정의
struct Point{
	ll x,y,n;
};
Point operator - (Point a, Point b){
	return {a.x-b.x, a.y-b.y, a.n};
}
ll ccw(Point a, Point b){
	return a.x * b.y - a.y * b.x;
}

int N;
ll xbase = 0, ybase = 1e9;
ll X[5050], Y[5050];
vector<Point> v;

int dp1[5050][5050], dp2[5050][5050];
int prev1[5050][5050], prev2[5050][5050];

int main(){
	scanf("%d",&N);
	for(int i=1;i<=N;i++){
		scanf("%lld%lld",&X[i],&Y[i]);
		if( ybase > Y[i] ){
			ybase = Y[i]; xbase = X[i];
		}
	}

	// 발뒤꿈치를 원점으로 하도록 점들을 평행이동시키자
	for(int i=1;i<=N;i++){
		X[i] -= xbase; Y[i] -= ybase;
		if( X[i] == 0 && Y[i] == 0 ) continue;
		v.push_back({X[i], Y[i], i});
	}

	// 나머지 점들(1,2,...,N-1)을 모두 반시계방향으로 정렬
	sort( v.begin(), v.end() , [](Point& a, Point& b){
		return ccw(a,b) > 0;
	} );

	v.push_back({0,0,0});
	
	// i를 고정시키고 슬라이딩 윈도우 기법으로 dp1[i][j], dp2[i][j]를 모두 채우자
	for(int i=0;i<v.size();i++){

		vector<Point> L,R;
		for(int j=0;j<i;j++){
			if( ccw(v[j], v[i]) == 0 ) continue;
			R.push_back(v[j]);
		}
		for(int j=i+1;j<v.size();j++){
			if( j != v.size()-1 && ccw(v[j], v[i]) == 0 ) continue;
			L.push_back(v[j]);
		}
		// dp1 채우기
		sort(L.begin(), L.end(), [i](Point a, Point b){
			return ccw(a-v[i], b-v[i]) > 0;
		});
		sort(R.begin(), R.end(), [i](Point a, Point b){
			return ccw(a-v[i], b-v[i]) > 0;
		});

		int pos = -1;
		int mx = 0, mxx = 0;

		for(auto p : L){
			while( pos+1 < R.size() && ccw( v[i]-p , R[pos+1]-p ) < 0 ){
				pos++;
				if( mx < dp2[ R[pos].n ][ v[i].n ] ){
					mx = dp2[ R[pos].n ][ v[i].n ];
					mxx = R[pos].n;
				}
			}

			if( dp1[ v[i].n ][ p.n ] < mx+1 ){
				dp1[ v[i].n ][ p.n ] = mx + 1;
				prev1[ v[i].n ][ p.n ] =mxx;
			//	printf("dp1[ %lld ][ %lld ] = %d   prev = %d \n", v[i].n, p.n, mx+1, mxx );
			}
			
		}

		// dp2 채우기
		sort(L.begin(), L.end(), [i](Point a, Point b){
			return ccw(a-v[i], b-v[i]) < 0;
		});
		sort(R.begin(), R.end(), [i](Point a, Point b){
			return ccw(a-v[i], b-v[i]) < 0;
		});

		pos = -1; mx = 0, mxx = 0;
		for(auto p : L){
			if( p.n == 0 ) continue;
			while( pos+1 < R.size() && ccw( v[i]-p , R[pos+1]-p ) > 0 ){
				pos++;
				if( mx < dp1[ R[pos].n ][ v[i].n ] ){
					mx = dp1[ R[pos].n ][ v[i].n ];
					mxx = R[pos].n;
				}
			}

			// 골은 적어도 두번째 점부터 시작
			if( mx >= 1 && dp2[ v[i].n ][ p.n ] < mx+1 ){
			//	printf("dp2[ %lld ][ %lld ] = %d   prev = %d \n", v[i].n, p.n, mx+1, mxx );
				dp2[ v[i].n ][ p.n ] = mx + 1;
				prev2[ v[i].n ][ p.n ] = mxx;
			}
			
		}
	}

	int mx = -1, mxx = 0;
	for(int i=1;i<=N;i++){
		if( mx < dp1[i][0] ){
			mx = dp1[i][0];
			mxx = i;
		}
	}

	// 발자국을 만들수 없는 경우 (발가락이 1개 이하)
	if( mx < 3 ){
		printf("0\n");
		return 0;
	}

	vector<pair<ll,ll>> ansv;
	int cur = mxx, nxt = 0;
	while( true ){
		//printf("%d %d\n",cur,nxt);
		ansv.push_back({X[cur]+xbase, Y[cur]+ybase});
		if( dp1[cur][nxt] == 1 ) break;
		int pre = prev1[cur][nxt];
		nxt = cur;
		cur = pre;

		//printf("%d %d\n",cur,nxt);
		ansv.push_back({X[cur]+xbase, Y[cur]+ybase});
		pre = prev2[cur][nxt];
		nxt = cur;
		cur = pre;
	}
	ansv.push_back({xbase, ybase});

	printf("%d\n", mx+1);
	reverse( ansv.begin(), ansv.end() );
	for(auto e : ansv) printf("%lld %lld\n",e.first, e.second);
}

Compilation message (stderr)

footprint.cpp: In function 'int main()':
footprint.cpp:114:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<v.size();i++){
              ~^~~~~~~~~
footprint.cpp:121:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=i+1;j<v.size();j++){
                 ~^~~~~~~~~
footprint.cpp:122:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if( j != v.size()-1 && ccw(v[j], v[i]) == 0 ) continue;
        ~~^~~~~~~~~~~~~
footprint.cpp:137:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while( pos+1 < R.size() && ccw( v[i]-p , R[pos+1]-p ) < 0 ){
           ~~~~~~^~~~~~~~~~
footprint.cpp:164:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while( pos+1 < R.size() && ccw( v[i]-p , R[pos+1]-p ) > 0 ){
           ~~~~~~^~~~~~~~~~
footprint.cpp:91:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&N);
  ~~~~~^~~~~~~~~
footprint.cpp:93:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld%lld",&X[i],&Y[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 12 / 12
• Subtask 3: 29 / 29
• Subtask 4: 45 / 45