oj.uz

Submission #17979

# Submission time Handle Problem Language Result Execution time Memory
17979 2016-01-16T15:57:39 Z gs14004 Demarcation (BOI14_demarcation) C++14
15 / 100
 500 ms 2848 KB 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <numeric>
#include <deque>
#include <bitset>
#include <iostream>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;
const int oo = 1e9;

int n;
vector<pi> a;

lint ccw(pi a, pi b, pi c){
	int dx1 = b.first - a.first;
	int dy1 = b.second - a.second;
	int dx2 = c.first - a.first;
	int dy2 = c.second - a.second;
	return 1ll * dx1 * dy2 - 1ll * dy1 * dx2;
}

void normalize(vector<pi> &v){
	int minx = 1e9, miny = 1e9;
	for(auto &i : v){
		minx = min(minx, i.first);
		miny = min(miny, i.second);
	}
	for(auto &i : v){
		i.first -= minx;
		i.second -= miny;
	}
	rotate(v.begin(), min_element(v.begin(), v.end()), v.end());
}

void reflect(vector<pi> &v){
	for(auto &i : v){
		i.first = -i.first;
	}
	normalize(v);
}

void turn(vector<pi> &v){
	for(auto &i : v){
		i = pi(-i.second, i.first);
	}
	normalize(v);
}

lint get_area(vector<pi> &v){
	lint ret = 0;
	for(int i=2; i<v.size(); i++){
		ret += ccw(v[0], v[i-1], v[i]);
	}
	return ret;
}

bool hapdong(vector<pi> &v1, vector<pi> &v2){
	normalize(v1);
	normalize(v2);
	for(int i=0; i<4; i++){
		turn(v2);
		if(v1 == v2) return 1;
	}
	reflect(v2);
	for(int i=0; i<4; i++){
		turn(v2);
		if(v1 == v2) return 1;
	}
	reverse(v2.begin(), v2.end());
	normalize(v2);
	for(int i=0; i<4; i++){
		turn(v2);
		if(v1 == v2) return 1;
	}
	reflect(v2);
	for(int i=0; i<4; i++){
		turn(v2);
		if(v1 == v2) return 1;
	}
	return 0;
}

void debug(vector<pi> &v){
	printf("%d ", v.size());
	for(auto &i : v) printf("(%d, %d) ", i.first, i.second);
	puts("");
}

bool mid(int s, int x, int e){
	return 1ll * (e-x) * (x-s) >= 0;
}

bool smid(int s, int x, int e){
	return 1ll * (e-x) * (x-s) > 0;
}

void cut_polygon(vector<pi> &in, vector<pi> &out1, vector<pi> &out2, int sx, int ex, int y){
	if(get_area(in) < 0) reverse(in.begin(), in.end());
	int p = min_element(in.begin(), in.end(), [&](const pi &a, const pi &b){
		return a.second < b.second;
	}) - in.begin();
	if(in[p].second >= y){
		out2 = in;
		return;
	}
	int cpos = 0;
	for(int i=0; i<in.size(); i++){
		pi p1 = in[p%in.size()];
		pi p2 = in[(p+1)%in.size()];
		p++;
		if(p1.second != p2.second && smid(p1.second, y, p2.second) && mid(sx, p1.first, ex)){
			if(cpos == 0) out1.push_back(p1);
			else out2.push_back(p1);
			out1.push_back(pi(p1.first, y));
			out2.push_back(pi(p1.first, y));
			cpos ^= 1;
		}
		else if(p1.second == y && p2.second == y && (mid(sx, p1.first, ex) || mid(sx, p2.first, ex))){
			if(sx != -1e9 && ex != 1e9 && smid(sx, p1.first, ex) && smid(sx, p2.first, ex)){
				out1 = in;
				out2.clear();
				return;
			}
			if(cpos == 0) out1.push_back(p1);
			else out2.push_back(p1);
			cpos ^= 1;
		}
		else{
			if(cpos == 0) out1.push_back(p1);
			else out2.push_back(p1);
		}
	}
	// printf("%d %d %d %d\n",sx,ex,sy,ey);
	// debug(out1), debug(out2);
}

int rsx = -1, rsy = -1, rex = -1, rey = -1;

bool non_enclosing(int sx, int ex, int y){
	for(int i=0; i<n; i++){
		pi p1 = a[i];
		pi p2 = a[(i+1)%n];
		if(p1.second != y || p2.second != y) continue;
		if(p1.first > p2.first) swap(p1, p2);
		if(smid(sx, p1.first, ex) && smid(sx, p2.first, ex)) return 0;
	}
	return 1;
}

void save_results(int sx, int ex, int y){
	for(int i=0; i<n; i++){
		pi p1 = a[i];
		pi p2 = a[(i+1)%n];
		if(p1.second != y || p2.second != y) continue;
		if(p1.first > p2.first) swap(p1, p2);
		if(p1.first <= sx) sx = max(sx, p2.first);
		if(p2.first >= ex) ex = min(ex, p1.first);
	}
	rsx = sx;
	rex = ex;
	rsy = y;
	rey = y;
}

struct swp{
	int yc, xc, act;
	bool operator<(const swp &b)const{
		return yc < b.yc;
	}
};

void solve(){
	vector<swp> event;
	set<int> line;
	for(int i=0; i<n; i++){
		pi p1 = a[i];
		pi p2 = a[(i+1)%n];
		if(p1.second == p2.second) continue;
		if(p1.second > p2.second) swap(p1, p2);
		event.push_back({p1.second, p1.first, 1});
		event.push_back({p2.second, p1.first, -1});
	}
	sort(event.begin(), event.end());
	for(int i=0; i<event.size(); ){
		int e = i;
		while(e < event.size() && event[e].yc == event[i].yc){
			if(event[e].act == 1) line.insert(event[e].xc);
			else line.erase(event[e].xc);
			e++;
		}
		if(line.empty()){
			i = e;
			continue;
		}
		auto it1 = line.begin(), it2 = ++line.begin();
		int sy = event[i].yc, ey = event[e].yc;
		while(it2 != line.end()){
			vector<pi> tmp, split1, split2;
			cut_polygon(a, split1, tmp, *it1, *it2, sy);
			tmp.clear();
			cut_polygon(a, tmp, split2, *it1, *it2, ey);
			tmp.clear();
			lint area1 = abs(get_area(split1));
			lint area2 = abs(get_area(split2));
			if(abs(area2 - area1) % (2 * *it2 - 2 * *it1) == 0){
				lint dx = (area2 - area1) / (2 * *it2 - 2 * *it1);
				lint dx2 = ey - sy;
				if(abs(dx) % 2 == dx2 % 2){
					lint q = (dx2 + dx) / 2;
					split1.clear();
					split2.clear();
					if(sy + q >= sy && sy + q <= ey){
						cut_polygon(a, split1, split2, *it1, *it2, sy + q);
						if(non_enclosing(*it1, *it2, sy+q) && hapdong(split1, split2)){
							save_results(*it1, *it2, sy+q);
							return;
						}
					}
				}
			}
			it1++;
			it1++;
			if(it1 == line.end()) break;
			it2++;
			it2++;
		}
		i = e;
	}
}

void point12(){
	int s = 0, e = 1e9;
	while(s != e){
		int m = (s+e)/2;
		vector<pi> v1, v2;
		cut_polygon(a, v1, v2, -oo, oo, m);
		if(abs(get_area(v1)) < abs(get_area(v2))){
			s = m+1;
		}
		else e = m;
	}
	vector<pi> v1, v2;
	cut_polygon(a, v1, v2, -oo, oo, s);
	if(hapdong(v1, v2)){
		vector<int> crd;
		for(int i=0; i<n; i++){
			pi p1 = a[i];
			pi p2 = a[(i+1)%n];
			if(p1.second == s && p2.second != s){
				crd.push_back(p1.first);
			}
			if(p2.second == s && p1.second != s){
				crd.push_back(p1.first);
			}
			if(smid(p1.second, s, p2.second)){
				for(int i=0; i<2; i++) crd.push_back(p1.first);
			}
		}
		sort(crd.begin(), crd.end());
		save_results(crd[1], crd[2], s);
	}
}

int main(){
	scanf("%d",&n);
	a.resize(n);
	for(int i=0; i<n; i++){
		scanf("%d %d",&a[i].first, &a[i].second);
	}
	for(int i=0; i<2; i++){
		solve();
		if(i == 1) swap(rsx, rsy), swap(rex, rey);
		if(rsx != -1){
			printf("%d %d %d %d",rsx, rsy, rex, rey);
			return 0;
		}
		for(int i=0; i<n; i++){
			swap(a[i].first, a[i].second);
		}
	}
	puts("NO");
}

Compilation message

demarcation.cpp: In function 'lint get_area(std::vector<std::pair<int, int> >&)':
demarcation.cpp:64:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=2; i<v.size(); i++){
                ^
demarcation.cpp: In function 'void debug(std::vector<std::pair<int, int> >&)':
demarcation.cpp:97:24: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<std::pair<int, int> >::size_type {aka long unsigned int}' [-Wformat=]
  printf("%d ", v.size());
                        ^
demarcation.cpp: In function 'void cut_polygon(std::vector<std::pair<int, int> >&, std::vector<std::pair<int, int> >&, std::vector<std::pair<int, int> >&, int, int, int)':
demarcation.cpp:120:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<in.size(); i++){
                ^
demarcation.cpp: In function 'void solve()':
demarcation.cpp:197:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<event.size(); ){
                ^
demarcation.cpp:199:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(e < event.size() && event[e].yc == event[i].yc){
           ^
demarcation.cpp: In function 'int main()':
demarcation.cpp:278:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
demarcation.cpp:281:43: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&a[i].first, &a[i].second);
                                           ^

Subtask #1
0 / 12.0

# Verdict Execution time Memory Grader output
1 Execution timed out 500 ms 2848 KB Execution timed out
2 Halted 0 ms 0 KB -

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2036 KB Output is correct
2 Correct 0 ms 2036 KB Output is correct
3 Correct 0 ms 2036 KB Output is correct
4 Correct 0 ms 2036 KB Output is correct
5 Correct 0 ms 2036 KB Output is correct
6 Correct 0 ms 2036 KB Output is correct
7 Correct 0 ms 2036 KB Output is correct
8 Correct 0 ms 2036 KB Output is correct
9 Correct 0 ms 2036 KB Output is correct
10 Correct 0 ms 2036 KB Output is correct
11 Correct 0 ms 2036 KB Output is correct
12 Correct 0 ms 2036 KB Output is correct
13 Correct 0 ms 2036 KB Output is correct
14 Correct 0 ms 2036 KB Output is correct
15 Correct 0 ms 2036 KB Output is correct
16 Correct 0 ms 2036 KB Output is correct
17 Correct 0 ms 2036 KB Output is correct
18 Correct 9 ms 2036 KB Output is correct
19 Correct 0 ms 2036 KB Output is correct
20 Correct 9 ms 2036 KB Output is correct
21 Correct 3 ms 2036 KB Output is correct
22 Correct 0 ms 2036 KB Output is correct
23 Correct 0 ms 2036 KB Output is correct
24 Correct 0 ms 2036 KB Output is correct
25 Correct 0 ms 2036 KB Output is correct
26 Correct 0 ms 2036 KB Output is correct
27 Correct 0 ms 2036 KB Output is correct
28 Correct 0 ms 2036 KB Output is correct
29 Correct 0 ms 2036 KB Output is correct
30 Correct 0 ms 2036 KB Output is correct

Subtask #3
0 / 23.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 2036 KB Output is correct
2 Correct 0 ms 2036 KB Output is correct
3 Correct 0 ms 2036 KB Output is correct
4 Correct 0 ms 2036 KB Output is correct
5 Correct 0 ms 2036 KB Output is correct
6 Correct 0 ms 2036 KB Output is correct
7 Correct 0 ms 2036 KB Output is correct
8 Correct 3 ms 2036 KB Output is correct
9 Correct 0 ms 2036 KB Output is correct
10 Correct 0 ms 2036 KB Output is correct
11 Correct 0 ms 2036 KB Output is correct
12 Correct 0 ms 2036 KB Output is correct
13 Correct 0 ms 2036 KB Output is correct
14 Correct 0 ms 2036 KB Output is correct
15 Correct 0 ms 2036 KB Output is correct
16 Correct 0 ms 2036 KB Output is correct
17 Correct 0 ms 2036 KB Output is correct
18 Correct 0 ms 2036 KB Output is correct
19 Correct 9 ms 2036 KB Output is correct
20 Correct 0 ms 2036 KB Output is correct
21 Correct 9 ms 2036 KB Output is correct
22 Correct 3 ms 2036 KB Output is correct
23 Correct 0 ms 2036 KB Output is correct
24 Correct 0 ms 2036 KB Output is correct
25 Correct 0 ms 2036 KB Output is correct
26 Correct 0 ms 2036 KB Output is correct
27 Correct 0 ms 2036 KB Output is correct
28 Correct 0 ms 2036 KB Output is correct
29 Correct 0 ms 2036 KB Output is correct
30 Correct 0 ms 2036 KB Output is correct
31 Correct 0 ms 2036 KB Output is correct
32 Correct 56 ms 2176 KB Output is correct
33 Correct 43 ms 2172 KB Output is correct
34 Correct 483 ms 2172 KB Output is correct
35 Correct 236 ms 2168 KB Output is correct
36 Execution timed out 500 ms 2172 KB Execution timed out
37 Halted 0 ms 0 KB -

Subtask #4
0 / 50.0

# Verdict Execution time Memory Grader output
1 Execution timed out 500 ms 2848 KB Execution timed out
2 Halted 0 ms 0 KB -