- -先mark了
http://blog.csdn.net/nyroro/article/details/45268767
https://vjudge.net/solution/1919422
#include <stdio.h> #include <algorithm> #include <string.h> using namespace std; #define maxn 110 struct point{ int x,y; point(){} point(int x,int y):x(x),y(y){} point operator+(const point&a)const{return point(x+a.x,y+a.y);} point operator-(const point&b)const{return point(x-b.x,y-b.y);} int operator*(const point&a)const{return x*a.y-y*a.x;} int norm()const{return x*x+y*y;} int operator <(const point&a)const{return (*this)*a>0||(*this)*a==0&&norm()<a.norm();} void out(){printf("x:%d y:%d\n",x,y);} void in(){scanf("%d%d",&x,&y);} }; //bool cmp(const point&a,const point&b ) //{ // return a*b>0||a*b==0&&a.norm()<b.norm(); //} int n; point src[maxn]; point dat[maxn]; int f[maxn][maxn]; int scan(int tot) { int res=0; memset(f,0,sizeof f); for(int i=1;i<tot;i++ ) { int j=i-1; while(j>=0&&dat[i]*dat[j]==0)j--; bool flag= j==i-1;//判断共线 while(j>=0) { int area=dat[j]*dat[i]; int k=j-1; while(k>=0&&(dat[j]-dat[i])*(dat[k]-dat[j])>0)k--; if(k>=0)area+=f[j][k]; if(flag)f[i][j]=area; res=max(res,area); j=k; } if(flag)for(int j=1;j<i;j++) f[i][j]=max(f[i][j],f[i][j-1]); } return res; } int solve(){ int res=0; for(int i=0;i<n;i++){ int m=0; for(int j=0;j<n;j++) if(src[j].y>src[i].y||(src[j].y==src[i].y&&src[j].x>=src[i].x)) dat[m++]=src[j]-src[i]; // printf("m:%d i:%d\n",m,i); //dat[0].out(); sort(dat,dat+m); //dat[0].out(); res=max(res,scan(m)); } return res; } int main(){ #ifdef shuaishuai freopen("C:\\Users\\hasee\\Desktop\\a.txt","r",stdin); // freopen("C:\\Users\\hasee\\Desktop\\b.txt","w",stdout); #endif int t; scanf("%d",&t); while(t--) { scanf("%d",&n); for(int i=0;i<n;i++ )src[i].in(); double ans=(double)solve()/2.0; printf("%.1f\n",ans); } return 0; }
时间: 2024-10-14 15:17:31