OJ-Problems-Source/HDOJ/4380_autoAC.cpp

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#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
using namespace std;
typedef long long LL;
const int N=105;
const int M=1005;
struct Point
{
LL x,y;
}P1[N],P2[M];
int f[N][N][N];
int n,m;
LL cross(Point a,Point b,Point s)
{
LL x1=a.x-s.x,y1=a.y-s.y;
LL x2=b.x-s.x,y2=b.y-s.y;
return x1*y2-x2*y1;
}
int dis2(Point a,Point b)
{
return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*((a.y-b.y));
}
int cmp(Point a,Point b)
{
if(cross(a,b,P1[0])>0)
return 1;
else return 0;
}
void init()
{
int i,t;
for(t=0,i=0;i<n;i++){
if((P1[i].y-P1[t].y)<0 || (P1[i].y-P1[t].y==0 && P1[i].x-P1[t].x<0))
t=i;
}
swap(P1[0],P1[t]);
sort(P1+1,P1+n,cmp);
}
int cal(int x,int y,int z)
{
int i;
int sum=0;
LL a,b,c;
for (i=0;i<m;i++)
{
a=cross(P1[y],P2[i],P1[x]);
b=cross(P1[z],P2[i],P1[y]);
c=cross(P1[x],P2[i],P1[z]);
if ((a>=0 && b>=0 && c>=0) || (a<=0 && b<=0 && c<=0))
{
sum++;
}
}
return sum;
}
int main()
{
int i,j,k;
int CA=0;
int ans=0;
while (scanf("%d%d",&n,&m)!=EOF)
{
ans=0;
memset(P1,0,sizeof(P1));
memset(P2,0,sizeof(P2));
memset(f,0,sizeof(f));
for (i=0;i<n;i++)
scanf("%I64d%I64d",&P1[i].x,&P1[i].y);
for (i=0;i<m;i++)
scanf("%I64d%I64d",&P2[i].x,&P2[i].y);
init();
for (i=2;i<n;i++){
for (j=1;j<i;j++){
f[0][j][i]=cal(0,j,i);
if (f[0][j][i]%2!=0) ans++;
}
}
for (i=2;i<n;i++)
for (j=1;j<i;j++)
for (k=j+1;k<i;k++){
if (cross(P1[k],P1[i],P1[j])>0)
f[j][k][i]=f[0][j][k]+f[0][k][i]-f[0][j][i];
else
f[j][k][i]=f[0][j][i]-(f[0][j][k]+f[0][k][j]);
if (f[j][k][i]%2!=0) ans++;
}
printf("Case %d: ",++CA);
printf("%d\n",ans);
}
}