23333，求出有多少斜率就好（还有斜率不存在），map随便搞一搞233333
1 #include<cstdio> 2 #include<cstring> 3 #include<cmath> 4 #include<map> 5 #define N 100005 6 #define inf 0x3f3f3f3f 7 #define eps 1e-8 8 using namespace std; 9 inline int ra() 10 { 11 int x=0,f=1; char ch=getchar(); 12 while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();} 13 while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();} 14 return x*f; 15 } 16 int x[1005],y[1005],n,ans; 17 map<double , bool > mp; 18 int main() 19 { 20 n=ra(); 21 for (int i=1; i<=n; i++) x[i]=ra(),y[i]=ra(); 22 for (int i=1; i<=n; i++) 23 for (int j=1; j<=n; j++) 24 if (i!=j) 25 { 26 if (x[i]-x[j]!=0) 27 { 28 if (mp[(double)(y[j]-y[i])/(x[j]-x[i])]==0) mp[(double)(y[j]-y[i])/(x[j]-x[i])]=1,ans++; 29 } 30 else if (!mp[1e9+7]) mp[1e9+7]=1,ans++; 31 } 32 printf("%d",ans); 33 return 0; 34 }