計算幾何模板

「`

// sgn返回x經過eps處理的符號，負數返回-1，正數返回1，x的絕對值如果足夠小，就返回0。

const double eps = 1e-8;

int sgn(double x)

```

double mysqrt(double x)

// pt是point的縮寫

//int版
struct pt 
pt(int
x,int
y) : x(x), y(y) 
};pt operator - (pt a, pt b) 
pt operator + (pt a, pt b) 
pt operator * (int a, pt p) 
pt operator * (pt p, int a) 
ints
qr(int x)
int norm(pt p) 
double dist (pt a, pt b) 
double len(pt p) 
void print(pt p) 
int dot(pt a, pt b) 
int det(pt a, pt b) 
int det(pt a,pt b,pt o) 
double triarea(pt a, pt b, pt c) 
//double版
struct pt 
pt(double x, double y) : x(x), y(y) 
};double s
qr(double x)
pt operator - (pt a, pt b) 
pt operator + (pt a, pt b) 
pt operator * (double a, pt p) 
pt operator * (pt p, double a) 
double norm(pt p) 
double dist (pt a, pt b) 
void print(pt p) 
double len(pt p) 
double dot(pt a, pt b) 
double det(pt a, pt b) 
double det(pt a,pt b,pt o) 
double triarea(pt a, pt b, pt c) 
pt rotate(pt p, double a)

struct sg 

sg(pt s, pt t) : s(s), t(t) 
sg(double a, double b, double c, double d) : s(a, b), t(c, d) 
};bool ptonsegment(pt s, pt t, pt a) 
bool ptonsegment(pt p, pt a, pt b) 
bool ptonline(pt p, pt s, pt t) 
bool sgonline(sg seg, pt ls, pt lt) 
pt ptlineproj(pt s, pt t, pt p) 
bool parallel(pt a, pt b, pt s, pt t) 
double ptsegmentdist(pt a, pt b, pt p) 
bool segcro(sg u,sg v)   /** 判斷線段是否相交 */  

//由三個點求平面方程

//平面方程a*x+b*y+c*z+d=0
;int a = ((a[2].y-a[1].y)*(a[3].z-a[1].z)-(a[2].z-a[1].z)*(a[3].y-a[1].y));
int b = ((a[2].z-a[1].z)*(a[3].x-a[1].x)-(a[2].x-a[1].x)*(a[3].z-a[1].z));
int c = ((a[2].x-a[1].x)*(a[3].y-a[1].y)-(a[2].y-a[1].y)*(a[3].x-a[1].x));
int d = -(a * a[1].x + b * a[1].y + c * a[1].z);
//重心
pt ********masscenter(pt a, pt b, pt c) 
//外心
pt circumcenter(pt a, pt b, pt c) 
//垂心
pt orthocenter(pt a, pt b, pt c)

#define nxt(x) ((x+1)%n)

struct polygon
polygon(vector
_poi):poi(_poi){}
int size()   
};int ptinpolygon(pt p, polygon &a) 
k = det(a.poi[nxt(i)]-a.poi[i], p-a.poi[i]);//double時要加sgn
d1 = a.poi[i].y - p.y;
d2 = a.poi[nxt(i)].y - p.y;
if (k > 0 && d1 <= 0 && d2 > 0) num++;
if (k < 0 && d2 <= 0 && d1 > 0) num--;
}return num != 0;
}

typedef

vector
convex;
typedef
vector
polygon;
// 排序比較函式，水平序
bool comp_less(pt a, pt b) 
int k = m;
for (int i = int(a.size()) - 2; i >= 0; --i) 
res.resize(m);
if (a.size() > 1) res.resize(m-1);
}

//求多邊形面積

double s(polygon &p)  

//求凸包的最遠距離

double convex_diameter(const convex &a, int &first, int &second) 
return ans;
}

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