记录编号 |
300113 |
评测结果 |
AAAAA |
题目名称 |
多边形面积 |
最终得分 |
100 |
用户昵称 |
AntiLeaf |
是否通过 |
通过 |
代码语言 |
C++ |
运行时间 |
0.000 s |
提交时间 |
2016-08-28 09:37:42 |
内存使用 |
0.00 MiB |
显示代码纯文本
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
const int maxn=110;
typedef struct Point{
double x,y;
Point(double x=0.0,double y=0.0):x(x),y(y){}
Point(const Point &A,const Point &B):x(B.x-A.x),y(B.y-A.y){}
Point operator-()const{
return Point(-x,-y);
}
Point operator+(const Point &b)const{
return Point(x+b.x,y+b.y);
}
Point operator-(const Point &b)const{
return *this+(-b);
}
}Vector;
double Cross(const Vector&,const Vector&);
double Area(const Point&,const Point&,const Point&);
int n;
Point a[maxn];
double ans=0.0;
inline int MAIN(){
#define MINE
#ifdef MINE
freopen("areas.in","r",stdin);
freopen("areas.out","w",stdout);
#endif
scanf("%d",&n);
for(int i=1;i<=n;i++)scanf("%lf%lf",&a[i].x,&a[i].y);
for(int i=2;i<n;i++)ans+=Area(a[1],a[i],a[i+1]);
printf("%.0lf",ans);
return 0;
}
double Cross(const Vector &A,const Vector &B){
return A.x*B.y-B.x*A.y;
}
double Area(const Point &A,const Point &B,const Point &C){
return Cross(Vector(A,B),Vector(A,C))/2.0;
}
int hzoier=MAIN();
int main(){;}