第一次在ubuntu下写程序,鼓捣了N久终于可以写东西了.从安装操作系统，编译软件，编译环境...
感觉自己弱成渣渣了...
一道水题 调了N久...
各种悲催..
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;struct Point2D{ double x,y; }mesh[33][33],p[4][33];
struct Vector2D{ double x,y; };
Vector2D operator-(Point2D a,Point2D b)
{Vector2D v;v.x=b.x-a.x;v.y=b.y-a.y;return v;
}double operator^(Vector2D a,Vector2D b){return fabs(a.x*b.y-b.x*a.y);
}Point2D getPoint( Point2D a,Point2D b,Point2D c,Point2D d )
{Point2D temp;temp.x=((a.x*((c-b)^(d-b)))+(b.x*((c-a)^(d-a))))/(((c-b)^(d-b))+((c-a)^(d-a)));temp.y=((a.y*((c-b)^(d-b)))+(b.y*((c-a)^(d-a))))/(((c-b)^(d-b))+((c-a)^(d-a)));return temp;
}double Area( Point2D a,Point2D b,Point2D c,Point2D d ){return (fabs((c-a)^(d-a))+fabs((c-b)^(d-b))+fabs((a-c)^(b-c))+fabs((a-d)^(b-d)))/4;
}int main()
{//freopen( "input.txt","r",stdin );//freopen( "output.txt","w",stdout );int N;while( scanf("%d",&N)!=EOF ){if( N==0 )break;memset(p,0,sizeof(p));p[0][0].x=0; p[0][0].y=0; p[0][N+1].x=1; p[0][N+1].y=0;p[1][0].x=0; p[1][0].y=1; p[1][N+1].x=1; p[1][N+1].y=1;for( int i=0;i<2;i++ ) for( int j=1;j<=N;j++ )scanf( "%lf",&p[i][j].x ),p[i][j].y=i%2;for( int i=2;i<4;i++ ) for( int j=1;j<=N;j++ )scanf( "%lf",&p[i][j].y ),p[i][j].x=i%2;for( int i=0;i<=N+1;i++ ){for( int j=0;j<=N+1;j++ ){//printf( "i=%d j=%d ",i,j );if( i==0 ) { mesh[i][j]=p[0][j];continue; }if( i==N+1 ) { mesh[i][j]=p[1][j];continue; }if( j==0 ) { mesh[i][j]=p[2][i];continue; }if( j==N+1 ) { mesh[i][j]=p[3][i];continue; }//mesh[i][j].x=0.1;mesh[i][j].y=0.1;printf( "(%lf,%lf) ",mesh[i][j].x,mesh[i][j].y );mesh[i][j]=getPoint( p[0][j],p[1][j],p[2][i],p[3][i] );//printf( "(%lf,%lf) ",mesh[i][j].x,mesh[i][j].y );}//printf( "\n" );}
/*for( int i=0;i<=N+1;i++ ){for( int j=0;j<=N+1;j++ )printf( "(%lf,%lf) ",mesh[i][j].x,mesh[i][j].y );printf( "\n" );}*/double ans=0;for( int i=0;i<=N;i++ )for( int j=0;j<=N;j++ )ans=max( ans,Area(mesh[i][j],mesh[i+1][j+1],mesh[i][j+1],mesh[i+1][j]) );printf( "%.6f\n",ans );}return 0;
}