9月22日 交汇的火力

 1 #include<iostream>
 2 using namespace std;
 3 int ans;
 4 double a[100001],b[100001],p[100001][3];
 5 int main ()
 6 {
 7     int n;
 8     cin>>n;
 9     double x,y;
10     int sb=0;
11     for (int i=1;i<=n;i++)
12         cin>>a[i]>>b[i];
13     for (int i=1;i<=n;i++)
14       for (int j=i+1;j<=n;j++)
15       {
16          if (a[i]==0&&a[j]==0) continue;
17            if (a[i]==a[j])
18              continue;
19            double l=a[i]-a[j];
20            double r=b[j]-b[i];
21            x=r/l;
22            y=a[i]*x+b[i];
23            int f=0;
24            for (int k=1;k<=sb;k++)
25            {
26                if (p[k][1]==x&&p[k][2]==y)
27                {
28                    f=1; break;
29                }
30            }
31            if (f==0)
32            {
33                sb++;
34               p[sb][1]=x;
35               p[sb][2]=y;
36               ans++;
37            }
38            
39       }
40     if (ans==0)
41       cout<<"No Fire Point.";
42     else
43     cout<<ans;
44 }