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답안 #230856

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
230856 2020-05-11T22:44:21 Z frodakcin Relay (COI16_relay) C++11
100 / 100
 143 ms 7928 KB 
#include <cstdio>
#include <cassert>

using ll = long long;
struct vec
{
public:
	ll x, y;
	vec(ll x=0, ll y=0) : x(x), y(y) {}
	void in(){scanf("%lld%lld", &x, &y);}
	ll operator / (vec o) const {return x*o.y-o.x*y;}
	ll operator * (vec o) const {return x*o.x+y*o.y;}

	vec& operator += (vec o) {return x+=o.x, y+=o.y, *this;}
	vec& operator -= (vec o) {return x-=o.x, y-=o.y, *this;}

	friend vec operator + (vec a, vec b) {return a += b;}
	friend vec operator - (vec a, vec b) {return a -= b;}
};

const int MN = 2e5 + 10;
int N, M, low[MN], high[MN], ans;
bool mayday[MN];
vec a[MN], b[MN];
struct ray
{
public: 
	vec s, d;
};
ray bot, top;
int main(void)
{
	scanf("%d", &N);
	for(int i=0;i<N;++i)
		a[i].in();
	scanf("%d", &M);
	for(int i=0;i<M;++i)
		b[i].in(), b[i+M]=b[i];//for convenience
	for(int i=0,l,r,m,u,v,z;i<N;++i)
	{
		vec x=a[i];
		//printf("INFO FOR (id: %d), (%lld, %lld) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n", i+1, x.x, x.y);
		z=0;
		vec d=b[z]-x;
		if(d/(b[1]-b[0]) == 0)
			d=b[++z]-x;
		if(d/(b[z+1]-b[z]) > 0)
		{
			l=z,r=M+z;
			for(;r-l>1;)
			{
				m=l+(r-l)/2;
				if(d/(b[m]-b[z]) < 0)
					r=m;
				else
					l=m;
			}
			u=l;
		}
		else
			u=z;
		u%=M;
		assert((b[u]-x)/(b[u+1]-x) <= 0);

		//b[u] is on the same side as a[i]
		d=b[u]-x;
		l=u,r=u+M;
		for(;r-l>1;)
		{
			m=l+(r-l)/2;
			if(d/(b[m]-b[u]) > 0)
				r=m;
			else
				l=m;
		}
		v=l%M;

		//printf("VALS: %d %d\n", u, v);
		assert((b[v]-x)/(b[v+1]-x) >= 0);

		//u<->v cut the convex hull
		//u is on closer side
		//lower hull: v...u
		{
			l=v,r=u;
			if(r<l)r+=M;
			--l;
			for(;r-l>1;)
			{
				m=l+(r-l)/2;
				if((b[m]-x)/(b[m+1]-b[m])>0)
					l=m;
				else
					r=m;
			}
			low[i] = r%M;
		}
		//upper hull: u...v
		{
			l=u,r=v;
			if(r<l) r+=M;
			--l;
			for(;r-l>1;)
			{
				m=l+(r-l)/2;
				if((b[m]-x)/(b[m+1]-b[m])<=0)
					l=m;
				else
					r=m;
			}
			high[i] = r%M;
		}

		//printf("\tLOW: (%lld, %lld)\n", b[low[i]].x, b[low[i]].y);
		//printf("\tHIGH: (%lld, %lld)\n", b[high[i]].x, b[high[i]].y);
		//printf("\n");

		assert((b[low[i]]-x)/(b[low[i]+1]-b[low[i]]) <= 0);
		assert((b[low[i]+M-1]-x)/(b[low[i]]-b[low[i]+M-1]) > 0);

		assert((b[high[i]]-x)/(b[high[i]+1]-b[high[i]]) > 0);
		assert((b[high[i]+M-1]-x)/(b[high[i]]-b[high[i]+M-1]) <= 0);
	}
	bot = {b[low[0]], b[low[0]]-a[0]};
	top = {b[high[0]], b[high[0]]-a[0]};
	vec bot0 = b[low[0]]-a[0];
	vec top0 = b[high[0]]-a[0];
	for(int i=1;i<N;++i)
	{
		if(bot.d/(a[i]-bot.s)>=0 || top.d/(a[i]-top.s)<=0)
			mayday[i] = 1;
		else if((a[i]-top.s)/(a[i]-bot.s) >= 0)
			mayday[i] = 1;
	}
	for(int i=1;i<N;++i)
		if(mayday[i])
		{
			//printf("MAYDAY: (id: %d), (%lld, %lld)\n", i+1, a[i].x, a[i].y);
			ray bot2 = {b[low[i]], b[low[i]]-a[i]};
			ray top2 = {b[high[i]], b[high[i]]-a[i]};

			if(bot0/bot2.d <= 0 && bot.d/bot2.d < 0)
				bot = bot2;
			if(top0/top2.d >= 0 && top.d/top2.d > 0)
				top = top2;
		}
	if((top.s-a[0])/(bot.s-a[0]) <= 0)
		return printf("%d\n", N-1), 0;
	for(int i=1;i<N;++i)
	{
		bool relay=0;
		if(bot.d/(a[i]-bot.s)>=0 || top.d/(a[i]-top.s)<=0)
			relay = 1;
		else if((a[i]-top.s)/(a[i]-bot.s) >= 0)
			relay = 1;
		if(relay)
		{
			++ans;
			//printf("RELAY: (id: %d), (%lld, %lld)\n", i+1, a[i].x, a[i].y);
		}
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message

relay.cpp: In function 'int main()':
relay.cpp:33:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
relay.cpp:36:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &M);
  ~~~~~^~~~~~~~~~
relay.cpp: In member function 'void vec::in()':
relay.cpp:10:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  void in(){scanf("%lld%lld", &x, &y);}
            ~~~~~^~~~~~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 6528 KB Output is correct
2 Correct 8 ms 6528 KB Output is correct
3 Correct 7 ms 6528 KB Output is correct
4 Correct 7 ms 6528 KB Output is correct
5 Correct 8 ms 6528 KB Output is correct
6 Correct 7 ms 6528 KB Output is correct
7 Correct 7 ms 6528 KB Output is correct
8 Correct 7 ms 6528 KB Output is correct
9 Correct 8 ms 6528 KB Output is correct
10 Correct 7 ms 6656 KB Output is correct

Subtask #2
19.0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 6528 KB Output is correct
2 Correct 8 ms 6528 KB Output is correct
3 Correct 7 ms 6528 KB Output is correct
4 Correct 7 ms 6528 KB Output is correct
5 Correct 8 ms 6528 KB Output is correct
6 Correct 7 ms 6528 KB Output is correct
7 Correct 7 ms 6528 KB Output is correct
8 Correct 7 ms 6528 KB Output is correct
9 Correct 8 ms 6528 KB Output is correct
10 Correct 7 ms 6656 KB Output is correct
11 Correct 10 ms 6656 KB Output is correct
12 Correct 11 ms 6656 KB Output is correct
13 Correct 10 ms 6656 KB Output is correct
14 Correct 10 ms 6656 KB Output is correct
15 Correct 10 ms 6656 KB Output is correct
16 Correct 10 ms 6656 KB Output is correct
17 Correct 10 ms 6656 KB Output is correct
18 Correct 10 ms 6528 KB Output is correct
19 Correct 10 ms 6656 KB Output is correct
20 Correct 10 ms 6656 KB Output is correct

Subtask #3
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 6528 KB Output is correct
2 Correct 8 ms 6528 KB Output is correct
3 Correct 7 ms 6528 KB Output is correct
4 Correct 7 ms 6528 KB Output is correct
5 Correct 8 ms 6528 KB Output is correct
6 Correct 7 ms 6528 KB Output is correct
7 Correct 7 ms 6528 KB Output is correct
8 Correct 7 ms 6528 KB Output is correct
9 Correct 8 ms 6528 KB Output is correct
10 Correct 7 ms 6656 KB Output is correct
11 Correct 57 ms 7416 KB Output is correct
12 Correct 58 ms 7416 KB Output is correct
13 Correct 54 ms 7416 KB Output is correct
14 Correct 54 ms 7416 KB Output is correct
15 Correct 66 ms 7416 KB Output is correct
16 Correct 66 ms 7416 KB Output is correct
17 Correct 64 ms 7416 KB Output is correct
18 Correct 66 ms 7420 KB Output is correct
19 Correct 65 ms 7416 KB Output is correct
20 Correct 64 ms 7416 KB Output is correct

Subtask #4
43.0 / 43.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 6528 KB Output is correct
2 Correct 8 ms 6528 KB Output is correct
3 Correct 7 ms 6528 KB Output is correct
4 Correct 7 ms 6528 KB Output is correct
5 Correct 8 ms 6528 KB Output is correct
6 Correct 7 ms 6528 KB Output is correct
7 Correct 7 ms 6528 KB Output is correct
8 Correct 7 ms 6528 KB Output is correct
9 Correct 8 ms 6528 KB Output is correct
10 Correct 7 ms 6656 KB Output is correct
11 Correct 10 ms 6656 KB Output is correct
12 Correct 11 ms 6656 KB Output is correct
13 Correct 10 ms 6656 KB Output is correct
14 Correct 10 ms 6656 KB Output is correct
15 Correct 10 ms 6656 KB Output is correct
16 Correct 10 ms 6656 KB Output is correct
17 Correct 10 ms 6656 KB Output is correct
18 Correct 10 ms 6528 KB Output is correct
19 Correct 10 ms 6656 KB Output is correct
20 Correct 10 ms 6656 KB Output is correct
21 Correct 57 ms 7416 KB Output is correct
22 Correct 58 ms 7416 KB Output is correct
23 Correct 54 ms 7416 KB Output is correct
24 Correct 54 ms 7416 KB Output is correct
25 Correct 66 ms 7416 KB Output is correct
26 Correct 66 ms 7416 KB Output is correct
27 Correct 64 ms 7416 KB Output is correct
28 Correct 66 ms 7420 KB Output is correct
29 Correct 65 ms 7416 KB Output is correct
30 Correct 64 ms 7416 KB Output is correct
31 Correct 114 ms 7416 KB Output is correct
32 Correct 118 ms 7544 KB Output is correct
33 Correct 89 ms 7344 KB Output is correct
34 Correct 91 ms 7416 KB Output is correct
35 Correct 136 ms 7416 KB Output is correct
36 Correct 143 ms 7416 KB Output is correct
37 Correct 137 ms 7416 KB Output is correct
38 Correct 133 ms 7416 KB Output is correct
39 Correct 125 ms 7288 KB Output is correct
40 Correct 127 ms 7928 KB Output is correct