hdu 1221 Rectangle and Circle

2015-12-21 · 1 min read · 计算几何

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
************************************************ */

 1#include <iostream>
 2#include <string.h>
 3#include <stdio.h>
 4#include <algorithm>
 5#include <cmath>
 6#define eps 1e-8
 7using namespace std;
 8struct point
 9{
10    double x;
11    double y;
12}circle,a,b,c,d;
13double r;
14double dis(point &a,point &b)
15{
16    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
17}

bool ok()
{

 1        if(dis(a,circle)<r && dis(b,circle) <r && dis(c,circle)<r && dis(d,circle) <r)
 2        return false;
 3        if(circle.x>=a.x && circle.x<=b.x)
 4        {
 5            if(fabs(circle.y-a.y) <= r || fabs(circle.y-b.y) <= r)
 6           return true;
 7        }
 8        if((circle.y >= a.y && circle.y <=b.y) || (circle.y>=b.y && circle.y<=a.y))
 9        {
10            if(fabs(circle.x-a.x) <=r || fabs(circle.x-b.x) <=r)
11            return true;
12        }
13        if(dis(a,circle)<=r || dis(b,circle) <=r || dis(c,circle)<=r || dis(d,circle) <=r)
14        return true;
15        return false;
16}
17int main()
18{
19    #ifndef ONLINE_JUDGE
20	freopen("code/in.txt","r",stdin);
21    #endif
22    int t;
23    scanf("%d",&t);
24    while(t--)
25    {
26        scanf("%lf %lf %lf %lf %lf %lf %lf",&circle.x,&circle.y,&r,&a.x,&a.y,&b.x,&b.y);
27        if(a.x > b.x)
28        swap(a,b);
29        c.x=a.x,c.y=b.y;
30        d.x=b.x,d.y=a.y;

 1    if (ok())
 2    {
 3	puts("YES");
 4    }
 5    else
 6    {
 7	puts("NO");
 8    }
 9    }
10    return 0;
11}