Submission #2118288

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Source Code Expand

#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

#define pb push_back
#define fr first
#define sc second

const long double EPS = 0.00000000001;

struct BIT{
	int siz;
	int a[(1<<16)+10];
	void init(int siz_ = 1<<16){
		siz = siz_;
		for(int i = 1 ; i <= siz ; i ++){
			a[i] = 0;
		}
	}
	void add(int k,int x = 1){
		while(k <= siz){
			a[k] += x;
			k += k&-k;
		}
	}
	int sum(int k){
		int ret = 0;
		while(k > 0){
			ret += a[k];
			k -= k&-k;
		}
		return ret;
	}
}bit;

int N;
long double A[4002];
long double B[4002];
long double C[4002];

int inv(vector<pair<long double,long double>> *vec){
	/*for(int i = 0 ; i < vec->size() ; i ++){
		cout << (*vec)[i].fr << " " << (*vec)[i].sc << endl;
	}*/
	
	vector<pair<long double,int>> a;
	for(int i = 0 ; i < vec->size() ; i ++){
		a.pb(pair<long double,int>((*vec)[i].sc,i+1));
	}
	sort(a.begin(),a.end());
	int ret = 0;
	bit.init();
	for(int i = 0 ; i < a.size() ; i ++){
		ret += bit.sum(a[i].sc);
		bit.add(a[i].sc);
	}
	return N*(N-1)/2-ret;
}

long double sol(){
	long double l = -100000000.0 , r = 100000000.0;
	while(l+EPS < r){
		long double m = (l+r)/2.0;
		vector<pair<long double,long double>> vec;
		for(int i = 1 ; i <= N ; i ++){
			vec.pb(pair<long double,long double>((C[i]-A[i]*m)/B[i],-A[i]/B[i]));
		}
		sort(vec.begin(),vec.end());
		if(inv(&vec)*4 <= N*(N-1))r = m;
		else l = m;
	}
	return l;
}

int main(){
	cout.precision(20);
	
	scanf("%d",&N);
	for(int i = 1 ; i <= N ; i ++){
		cin >> A[i] >> B[i] >> C[i];
	}
	long double X = sol();
	
	for(int i = 1 ; i <= N ; i ++){
		swap(A[i],B[i]);
	}
	long double Y = sol();
	
	cout << X << " " << Y << endl;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:86:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&N);
                ^

Judge Result