【计算几何】Triangles HUST 1607

#include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
#include<map>
#include<queue>
#include<cmath>
#include<algorithm>
#include<deque>
typedef long long LL;
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
const int INF=0x3f3f3f3f;
const int N = 200+10;
//
struct point
{
double x,y;
} poi
;
int num;
typedef pair<double,double>PII;
PII temp[220];
map<PII,int>mp;
int tot;
int ma

;

int GetId(PII s)
{
if(mp.find(s)!=mp.end())
return mp[s];
mp[s]=++tot;
return tot;
}

struct V   //两点式
{
point start;
point end;
};
V change(V a)   //两点式起点化为 0，0
{
V b;
b.start.x = 0;
b.start.y = 0;
b.end.x = a.end.x - a.start.x;
b.end.y = a.end.y - a.start.y;
return b;
}
double cross_mul(V a,V b)
{
double result;
V aa = change(a);
V bb = change(b);
result = aa.end.x*bb.end.y - aa.end.y*bb.end.x;
return result;
}
const double eps=1e-6;
bool Judge(point a,point b,point c)
{
V aa,bb;
aa.start = a;
aa.end = b;
bb.start = a;
bb.end = c;
double ans = cross_mul(aa,bb);
if(fabs(ans)<eps) return false;
return true;
}
bool pan(point a,point b,point c)
{
if((a.x - b.x) * (c.x - b.x) < 0 && (a.y - b.y) * (c.y - b.y) < 0)
return true;
return false;
}

int main()
{
PII temp;
int n,m;
while(~scanf("%d%d",&n,&m))
{
mp.clear();
tot=0;
num=0;
for(int i = 1; i <= n; i++)
{
cin>>temp.first>>temp.second;
int id = GetId(temp);
poi[id].x=temp.first;
poi[id].y=temp.second;
}
//        printf("%d\n",tot);

PII x,y;
memset(ma,0,sizeof(ma));
for(int i=0; i<m; ++i)
{
cin>>x.first>>x.second>>y.first>>y.second;
int u=GetId(x);
int v=GetId(y);
ma[u][v]=ma[v][u]=1;
}
for(int k=1; k<=tot; k++)
for(int i=1; i<=tot; i++)
for(int j=1; j<=tot; j++)
{
if(!Judge(poi[i],poi[j],poi[k])&&ma[i][k])
{
//printf("%d %d %d\n",i,k,j);
if(pan(poi[i],poi[j],poi[k]))
{
//puts("??");
ma[i][j]=ma[j][i]=ma[j][k]=ma[k][j]=1;
}
else if(ma[k][j])
{
//puts("**");
ma[i][j]=ma[j][i]=1;
}
}
}
//        for(int i = 1; i <= tot; i++)
//        {
//            for(int j = 1; j <= tot; j++)
//                printf("ma[%d][%d] = %d  ",i,j,ma[i][j]);
//            puts("");
//        }
int ans=0;
for(int i=1; i<=n; i++)
for(int j=i+1; j<=n; j++)
for(int k=j+1; k<=n; k++)
if(ma[i][j] && ma[j][k] && ma[i][k] && Judge(poi[i],poi[j],poi[k]))
{
//printf("%d %d %d\n",i,j,k);
ans++;
}
printf("%d\n",ans);
}
return 0;
}