hoj 13832 Fence 凸包

凸包学习了

#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <queue>
#include <limits.h>
#include <string.h>
#include <vector>
#include <map>
#include <math.h>
#define LL long long
#define INF 2100000000
#define fi first
#define se second
#define lowbit(x) (x&(-x))
#define eps 5e-7
using namespace std;
const int maxn=(int)1e4 +30;
const int MOD=998244353;
struct point
{
    LL x,y;
    point() {}
    point(LL x,LL y):x(x),y(y) {}
    point operator -(const point& a)const
    {
        return point(x-a.x,y-a.y);
    }
    LL operator *(const point& a)const
    {
        return (x*a.y)-(y*a.x);
    }
    bool operator <(const point &a)const
    {
        if(x!=a.x)return x<a.x;
        return y<a.y;
    }
    void input()
    {
        scanf("%I64d%I64d",&x,&y);
    }
    void output()
    {
        printf("%I64d %I64d
",x,y);
    }
};
point p[maxn];
point cp[maxn];
int n;
int Andrew()
{
    sort(p,p+n);
    int m=0;
    for(int i=0; i<n; i++) // bottom half
    {
        while(m>1&&(cp[m-1]-cp[m-2])*(p[i]-cp[m-2])<=0) m--;
//        cout<<"i: "<<i<<" "<<"m: "<<m<<" "<<(cp[m-1]-cp[m-2])*(p[i]-cp[m-2])<<endl;
        cp[m++]=p[i];
    }
    int k=m;
    for(int i=n-2; i>=0; i--) // top half
    {
        while(m>k&&(cp[m-1]-cp[m-2])*(p[i]-cp[m-2])<=0)m--;
//        cout<<"i: "<<i<<" "<<"m: "<<m<<" "<<(cp[m-1]-cp[m-2])*(p[i]-cp[m-2])<<endl;
        cp[m++]=p[i];
    }
    if(n>1) m--;// p[0] will be insert again
    return m;
}
int main()
{
#ifdef shuaishuai
    freopen("C:\Users\hasee\Desktop\a.txt","r",stdin);
   // freopen("C:\Users\hasee\Desktop\b.txt","w",stdout);
#endif
    while(scanf("%d",&n)!=EOF,n!=0  )
    {

        for(int i=0; i<n; i++)p[i].input();
        LL a=0,b=0;
        int m=Andrew();


        for(int i=0; i<m; i++)
        {
            LL dy=abs(cp[i].y-cp[(i+1)%m].y) ;
            LL dx=abs(cp[i].x-cp[(i+1)%m].x  );
            b+=min(dy,dx);
            a+=abs(dy-dx);
        }
        cout<<a<<" "<<b<<endl;
//        printf("%I64d %I64d
",a,b);

    }
    return 0;
}