「POJ - 2318」TOYS (叉乘)

#include <cstdio>
#define N 50001
int n,m;
int x1,y1,x2,y2,u[N],l[N];
int ans[N];
int xmul(int x1,int y1,int x2,int y2){
	return (x1*y2)-(x2*y1);
}
int main(){
	while(scanf("%d",&n),n){
		scanf("%d%d%d%d%d",&m,&x1,&y1,&x2,&y2);
		for(int i=0;i<n;++i)
			scanf("%d%d",u+i,l+i),ans[i]=0;
		ans[n]=0;
		for(int i=0,j,x,y;i<m;++i){
			scanf("%d%d",&x,&y);
			for(j=0;j<n;++j)
				if(xmul(x-l[j],y-y2,u[j]-l[j],y1-y2)<=0)
					break;
			++ans[j];
		}
		for(int i=0;i<=n;++i)
			printf("%d: %d\n",i,ans[i]);
		puts("");
	}
}