【凸包板题】Gym - 101484E E. Double Fence

http://codeforces.com/gym/101484/problem/E

题解 凸包板题

#define _CRT_SECURE_NO_WARNINGS
#include<cmath>
#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
#define rep(i,t,n)  for(int i =(t);i<=(n);++i)
#define per(i,n,t)  for(int i =(n);i>=(t);--i)
#define mmm(a,b) memset(a,b,sizeof(a))

const int maxn = 2e5 + 10;
int a[maxn];
typedef long long ll;
const double eps = 1e-7;//eps用于控制精度
struct Point//点或向量
{
    double x, y;
    Point() {}
    Point(double x, double y) :x(x), y(y) {}
};
bool cmp1(Point a,Point b){
    if(a.x==b.x)return a.y<b.y;
    else return a.x<b.x;
}
struct triVec {
    double x, y,z;
    triVec() {}
    triVec(double x, double y,double z) :x(x), y(y),z(z) {}
};
typedef Point Vector;
Vector operator + (Vector a, Vector b)//向量加法
{
    return Vector(a.x + b.x, a.y + b.y);
}
Vector operator - (Vector a, Vector b)//向量减法
{
    return Vector(a.x - b.x, a.y - b.y);
}
Vector operator * (Vector a, double p)//向量数乘
{
    return Vector(a.x*p, a.y*p);
}
Vector operator / (Vector a, double p)//向量数除
{
    return Vector(a.x / p, a.y / p);
}
int dcmp(double x)//精度三态函数(>0,<0,=0)
{
    if (fabs(x) < eps)return 0;
    else if (x > 0)return 1;
    return -1;
}
bool operator == (const Point &a, const Point &b)//向量相等
{
    return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;
}
double Dot(Vector a, Vector b)//内积
{
    return a.x*b.x + a.y*b.y;
}
double Length(Vector a)//模
{
    return sqrt(Dot(a, a));
}
Vector Rotate(Vector a, double rad)//逆时针旋转
{
    return Vector(a.x*cos(rad) - a.y*sin(rad), a.x*sin(rad) + a.y*cos(rad));
}
double Cross(Vector a, Vector b)//外积
{
    return a.x*b.y - a.y*b.x;
}
double Distance(Point a, Point b)//两点间距离
{
    return sqrt((a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y));
}
int n, m;
double z;
//Point p[maxn];




Point f1[maxn];
Point f2[maxn];
Point result[maxn];
vector<Point> P;
int  top;
bool cmp(Point A, Point B)
{
    double ans = Cross(A - P[0], B - P[0]);
    if (dcmp(ans) == 0)
        return dcmp(Distance(P[0], A) - Distance(P[0], B)) < 0;
    else
        return ans > 0;
}
void Graham()//Graham凸包扫描算法
{
    for (int i = 1; i < P.size(); i++)//寻找起点
        if (P[i].y < P[0].y || (dcmp(P[i].y - P[0].y) == 0 && P[i].x < P[0].x))
            swap(P[i], P[0]);
    sort(P.begin()+1, P.end(), cmp);//极角排序，中心为起点
    result[0] = P[0];
    result[1] = P[1];
    top = 1;
    for (int i = 2; i < P.size(); i++)
    {
        while (Cross(result[top] - result[top - 1], P[i] - result[top - 1]) < 0 && top >= 1)
            top--;
        result[++top] = P[i];
    }
}

int main() {
    int n,m;
    cin>>n>>m;
    rep(i,1,n){scanf("%lf%lf",&f1[i].x,&f1[i].y);P.push_back(f1[i]);}
    rep(i,1,m){scanf("%lf%lf",&f2[i].x,&f2[i].y);P.push_back(f2[i]);}
    //if(n<=2||m<=2) return 0*printf("NO\n");
    Graham();
    sort(result,result+top,cmp);
    sort(f1+1,f1+n+1,cmp);
    sort(f2+1,f2+n+1,cmp);
    int f=1,ff=1;
    rep(i,1,n){
    if(!(f1[i]==result[i-1]))f=0;

    }
    if(n!=top+1)f=0;
    rep(i,1,m){
    if(!(f2[i]==result[i-1]))ff=0;
    }
    if(m!=top+1)f=0;
   /* rep(i,1,n)cout<<f1[i].x<<'*'<<f1[i].y<<' ';
    cout<<endl;
    rep(i,1,m)cout<<f2[i].x<<'*'<<f2[i].y<<' ';
    cout<<endl;
    rep(i,0,top)cout<<result[i].x<<'*'<<result[i].y<<' ';
    cout<<endl;*/
    if(f|ff)puts("YES");
    else puts("NO");


}