hdu 1221 Rectangle and Circle

http://acm.hdu.edu.cn/showproblem.php?pid=1221 题意：问圆和矩形是否相交 思路：主要特殊的包含情况，然后判断与线段相交。

/* ***********************************************
Author :111qqz
Created Time :2015年12月21日 星期一 21时38分22秒
File Name :code/hdu/rr1221.cpp
************************************************ */

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <algorithm>
#include <cmath>
#define eps 1e-8
using namespace std;
struct point
{
    double x;
    double y;
}circle,a,b,c,d;
double r;
double dis(point &a,point &b)
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

bool ok()
{

        if(dis(a,circle)<r && dis(b,circle) <r && dis(c,circle)<r && dis(d,circle) <r)
        return false;
        if(circle.x>=a.x && circle.x<=b.x)
        {
            if(fabs(circle.y-a.y) <= r || fabs(circle.y-b.y) <= r)
           return true;
        }
        if((circle.y >= a.y && circle.y <=b.y) || (circle.y>=b.y && circle.y<=a.y))
        {
            if(fabs(circle.x-a.x) <=r || fabs(circle.x-b.x) <=r)
            return true;
        }
        if(dis(a,circle)<=r || dis(b,circle) <=r || dis(c,circle)<=r || dis(d,circle) <=r)
        return true;
        return false;
}
int main()
{
    #ifndef ONLINE_JUDGE
	freopen("code/in.txt","r",stdin);
    #endif
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%lf %lf %lf %lf %lf %lf %lf",&circle.x,&circle.y,&r,&a.x,&a.y,&b.x,&b.y);
        if(a.x > b.x)
        swap(a,b);
        c.x=a.x,c.y=b.y;
        d.x=b.x,d.y=a.y;
    
    if (ok())
    {
	puts("YES");
    }
    else
    {
	puts("NO");
    }
    }
    return 0;
}