UVA 1382 - Distant Galaxy

 

#include <cstdio>
#include <algorithm>
using namespace std;
struct Point
{
    int x,y;
    bool operator < (const Point& a) const{
        return x<a.x;
    }
};
const int maxn=100+5;
Point p[maxn];
int n,m,y[maxn],on[maxn],on2[maxn],left[maxn];
int solve(){
    sort(p,p+n);
    sort(y,y+n);
    m=unique(y,y+n)-y;
    if(m<=2) return n;
    int ans=0;
    for(int a=0;a<m;a++){
        for(int b=a+1;b<m;b++){
            int ymin=y[a],ymax=y[b];
            int k=0;
            for(int i=0;i<n;i++){
                if(i==0 || p[i].x !=p[i-1].x){
                    k++;
                    on[k]=on2[k]=0;
                    left[k]=k==0?0:left[k-1]+on2[k-1]-on[k-1];
                }
                if(p[i].y>ymin && p[i].y<ymax) on[k]++;
                if(p[i].y>=ymin && p[i].y<=ymax) on2[k]++;
            }
            if(k<=2) return n;
            int M=0;
            for(int j=1;j<=k;j++){
                ans=max(ans,left[j]+on2[j]+M);
                M=max(M,on[j]-left[j]);
            }
        }
    }
    return ans;
}
int main(){
    int kase=0;
    while(scanf("%d",&n)==1 && n){
        for(int i=0;i<n;i++){
            scanf("%d%d",&p[i].x,&p[i].y);
            y[i]=p[i].y;
        }
        printf("Case %d: %d\n",++kase,solve());
    }
    return 0;
}