hud 4454 Stealing a Cake 解题报告

题意：给定一个点 一个圆，一个矩形，求点到圆上再到矩形的最短距离

解题思路：三分圆上点的弧度

解题代码：

#include <stdio.h>
#include <math.h>
double ans ;
double x1,y11,x2,y2,x,y,r,cx,cy;

void fen(double low ,double high)
{
    double dis(double a,double b,double c,double d);
    double dis1(double i , double j );

    double tx , ty;
    double ansmid1 ;
    double ansmid2 ;
    double mid1 = low+(high-low)*1/3;
    tx = x + r*sin(mid1);
    ty = y + r*cos(mid1);
    ansmid1 = dis(tx,ty,cx,cy) + dis1(tx,ty);
    //printf("%lf %lf %lf\n",tx,ty,ansmid1);
    double mid2 = low +(high - low)*2/3;
    tx = x + r*sin(mid2);
    ty = y + r*cos(mid2);
    ansmid2 = dis(tx,ty,cx,cy) + dis1(tx,ty);
    //printf("%lf %lf %lf\n",tx,ty,ansmid2);
    if(fabs(ansmid2 - ansmid1) < 0.00001)
    {
       ans = ansmid2;
       return ;
    }
    if(ansmid1 < ansmid2)
        fen(low,mid2);
    else
        fen(mid1,high);

}
void fen2(double low ,double high)
{
    double dis(double a,double b,double c,double d);
    double dis1(double i , double j );

    double tx , ty;
    double ansmid1 ;
    double ansmid2 ;
    double mid1 = low+(high-low)*1/4;
    tx = x + r*sin(mid1);
    ty = y + r*cos(mid1);
    ansmid1 = dis(tx,ty,cx,cy) + dis1(tx,ty);
    //printf("%lf %lf %lf %lf %lf\n",tx,ty,ansmid1,dis(tx,ty,cx,cy),dis1(tx,ty));
    double mid2 = low +(high - low)*2/4;
    tx = x + r*sin(mid2);
    ty = y + r*cos(mid2);
    ansmid2 = dis(tx,ty,cx,cy) + dis1(tx,ty);
    //printf("%lf %lf %lf\n",tx,ty,ansmid2);
    if(fabs(ansmid2 - ansmid1) < 0.00001)
    {
       
       if(ansmid2 < ans)
             ans = ansmid2;
       return ;
    }
    if(ansmid1 < ansmid2)
        fen2(low,mid2);
    else
        fen2(mid1,high);

}
double dis(double a,double b,double c,double d)
{
    return sqrt(pow(a-c,2)+pow(b-d,2));
}
double dis1(double i , double j )
{
 
    if(i >= x1 && i <= x2)
    {
        if(j > y11)
        {
            return fabs(j-y11);
        }
        else if(j < y2)
        {
            return  fabs(y2 - j);
        }
        else return 0 ;
    }
    else if(j >= y2 && j <= y11)
    {
        if(i < x1 )
        {  
            return fabs(x1 - i);
        }
        else if(i >x2 )
        {
            return fabs(i-x2);
        }
        else return 0 ;

    }
    else if(i < x1 && j > y11)
    {
        return dis(i,j ,x1, y11);
    }
    else if(i > x2 && j > y11)
    {
        return dis(i,j,x2,y11);
    }
    else if(i < x1 && j < y2)
    {
        return dis(i , j , x1, y2);
    }
    else return dis(i,j,x2,y2);
}
int main()
{
    while(scanf("%lf %lf",&cx,&cy) != EOF)
    {
        if(cx == 0 && cy == 0)
            break;
        scanf("%lf %lf %lf",&x,&y,&r);
        scanf("%lf %lf %lf %lf",&x1,&y11,&x2,&y2);
        double tempx, tempy;
        if(x1 < x2 && y11 > y2)
        {
            int p ;
        }
        else if(x1 < x2 && y11 < y2)
        {
            tempy = y11;
            y11 = y2;
            y2 = tempy;
        }
        else if(x1 > x2 && y11 > y2)
        {
            tempx = x1 ;
            x1 = x2;
            x2 = tempx;
        }
        else if(x1 > x2 && y11 < y2)
        {
            tempy = y11;
            y11 = y2;
            y2 = tempy;
            tempx = x1 ;
            x1 = x2;
            x2 = tempx;

        }
        //printf("%lf %lf %lf %lf\n",x1,y11,x2,y2);
        fen(0,3.1415926*2);
        fen2(0,3.1415926*2);
        printf("%.2lf\n",ans);
    }
    return 0 ;
}