Submission #7287509

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
#define ll long long
int n;
struct node{
	double x,y;
}k[102];
double dis(double a,double b){return sqrt(a*a+b*b);}
bool cmp(node a,node b){return a.x>b.x;}
bool cmp2(node a,node b){return a.x<b.x;}
bool cmp3(node a,node b){return a.y>b.y;}
bool cmp4(node a,node b){return a.y<b.y;}
bool cmp5(node a,node b){return dis(a.x,a.y)>dis(b.x,b.y);}
bool cmp6(node a,node b){return dis(a.x,a.y)<dis(b.x,b.y);}
double ans;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>k[i].x>>k[i].y;
	sort(k+1,k+n+1,cmp);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	sort(k+1,k+n+1,cmp2);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	sort(k+1,k+n+1,cmp3);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	sort(k+1,k+n+1,cmp4);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	sort(k+1,k+n+1,cmp5);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	sort(k+1,k+n+1,cmp6);
	for(int i=1;i<=n;i++){
		double xx=k[i].x,yy=k[i].y;
		for(int j=1;j<=n;j++)
			if(i!=j&&dis(xx+k[j].x,yy+k[j].y)>dis(xx,yy))
				xx+=k[j].x,yy+=k[j].y;
		ans=max(ans,dis(xx,yy));
	}
	srand(time(0));
	for(int i=1;i<=1000;i++){
		int pd[102],num=0;
		double xx=0,yy=0;
		memset(pd,0,sizeof(pd));
		for(int j=1;j<=n;j++){
			int op=rand()%n+1;
			while(pd[op])op=rand()%n+1;
			if(dis(xx+k[op].x,yy+k[op].y)>dis(xx,yy)) 
				xx+=k[op].x,yy+=k[op].y;
			pd[op]=1;
		}
		ans=max(ans,dis(xx,yy));
	}
	printf("%.15lf",ans);
    return 0;
}

Submission Info

Judge Result