Submission #932110

#	Time	Username	Problem	Language	Result	Execution time	Memory
932110		vjudge1	SIR (COI15_sir)	C++17	100 / 100	310 ms	33428 KiB

sir

#include<bits/stdc++.h>
#define int long long
using namespace std;
int N, M, total=0, vis=0;
vector<pair<int, int> > bigger;
vector<pair<int, int> > smaller;
vector<pair<int, int> > p;
int bell=1, ans=0;
bool check(pair<int, int> a, pair<int, int> b, pair<int, int> c){
	return ((b.first-a.first)*(c.second-a.second)-(c.first-a.first)*(b.second-a.second))>0;
}
bool chack(pair<int, int> a, pair<int, int> b, pair<int, int> c){
	return ((b.first-a.first)*(c.second-a.second)-(c.first-a.first)*(b.second-a.second))<=0;
}
int get(pair<int, int> a, pair<int, int> b, pair<int, int> c){
	return abs(a.first*(b.second-c.second)+b.first*(c.second-a.second)+c.first*(a.second-b.second));
}
bool trapp(pair<int, int> a, int ind){
	int x=ind, y;
	if(ind==smaller.size()-1){
		y=0;
	}else{
		y=x+1;
	}
	return chack(a, smaller[x], smaller[y]);
}
bool troll(pair<int, int> a, int ind){
	int x=ind, y;
	if(ind==0){
		y=smaller.size()-1;
	}else{
		y=x-1;
	}
	return chack(a, smaller[x], smaller[y]);
}
void solve(){
	sort(p.begin(), p.end());
	smaller.push_back(p[0]);
	for(int i=1; i<M; i++){
		while(smaller.size()>=2 && check(smaller[smaller.size()-2], smaller[smaller.size()-1], p[i])){
			smaller.pop_back();
		}
		smaller.push_back(p[i]);
	}
	for(int i=M-2; i>=0; i--){
		while(smaller.size()>=2 && check(smaller[smaller.size()-2], smaller[smaller.size()-1], p[i])){
			smaller.pop_back();
		}
		smaller.push_back(p[i]);
	}
	if(M>1) smaller.pop_back();
}
signed main(){
	cin>>N;
	for(int i=1; i<=N; i++){
		int x, y; cin>>x>>y; bigger.push_back({x, y});
	}
	reverse(bigger.begin(), bigger.end());
	cin>>M;
	for(int i=1; i<=M; i++){
		int x, y; cin>>x>>y; p.push_back({x, y});
	}
	solve(); M=smaller.size();
	for(int i=0; i<M; i++){
		if(trapp(bigger[0], i) && troll(bigger[0], i)){
			vis=i; break;
		}
	}
	for(int i=0; i<bigger.size(); i++){
		while(!(trapp(bigger[i], vis) && troll(bigger[i], vis))){
			vis++; vis%=smaller.size();
		}
		if(i){
			int x=i-1;
			if(x==-1) x=N-1;
			int y=bell-1;
			if(y==-1) y=N-1;
			ans-=get(bigger[x], bigger[i], bigger[y]);
		}
		for(bell; check(bigger[i], smaller[vis], bigger[bell]); bell++, bell%=N){
			int x=bell-1;
			if(x==-1) x=N-1;
			ans+=get(bigger[i], bigger[x], bigger[bell]);
		}
		total=max(total, ans);
	}
	cout<<total;
}

Compilation message (stderr)

sir.cpp: In function 'bool trapp(std::pair<long long int, long long int>, long long int)':
sir.cpp:20:8: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |  if(ind==smaller.size()-1){
      |     ~~~^~~~~~~~~~~~~~~~~~
sir.cpp: In function 'int main()':
sir.cpp:69:16: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |  for(int i=0; i<bigger.size(); i++){
      |               ~^~~~~~~~~~~~~~
sir.cpp:80:7: warning: statement has no effect [-Wunused-value]
   80 |   for(bell; check(bigger[i], smaller[vis], bigger[bell]); bell++, bell%=N){
      |       ^~~~

• Subtask 1: 12 / 12
• Subtask 2: 39 / 39
• Subtask 3: 49 / 49