【UVALive】3695 Distant Galaxy（......）

题目

传送门：QWQ

分析

好喵啊~~~~

不会做

正解看蓝书P53吧

代码

#include <cstdio>
#include <algorithm>
using namespace std;
inline int read()
{
    int x = 0, f = 1; char ch = getchar();
    while (ch < '0' || ch > '9'){if (ch == '-')f = -1;ch = getchar();}
    while (ch >= '0' && ch <= '9'){x = x * 10 + ch - '0';ch = getchar();}
    return x * f;
}
struct Point{
    int x,y;
    bool operator < (const  Point& rhs) const{
        return x<rhs.x;
    }
};
const int maxn=105;
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++){P[i].x=read();P[i].y=read();y[i]=P[i].y;}
        printf("Case %d: %d\n",++kase,solve());
    }
    return 0;
}