OJ-Problems-Source/QUSTOJ/1008.cpp

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2016-04-28 08:51:47 +08:00
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
const double PI=3.1415926;
typedef struct
{
double x,y;
int vis;
}point_struct;
point_struct point[105];
int main()
{
//Initialize
memset(point,0,sizeof(point_struct)*105);
double r;
double line_length=0;
int n;
//Input
scanf("%d %lf",&n,&r);
for(int i=0;i<n;i++)
{
scanf("%lf %lf",&point[i].x,&point[i].y);
}
//Now start with the first point, currently : All of point.vis is 0 (false)
//At first we need some value to save states.
int isfirst=1;//It's the first point
double min_distance;
int min_distance_point;
int checked_point=0;
int checking_point=0;
while(checked_point<n-1)
{
//Now is checking "checking_point"
isfirst=1;
for(int i=0;i<n;i++)
{
if(point[i].vis||i==checking_point)
{
continue;
}
if(isfirst)
{
isfirst=0;
min_distance=sqrt((point[checking_point].x-point[i].x)*(point[checking_point].x-point[i].x)+(point[checking_point].y-point[i].y)*(point[checking_point].y-point[i].y));
min_distance_point=i;
}
else
{
double this_distance=sqrt((point[checking_point].x-point[i].x)*(point[checking_point].x-point[i].x)+(point[checking_point].y-point[i].y)*(point[checking_point].y-point[i].y));
if(min_distance>this_distance)
{
min_distance=this_distance;
min_distance_point=i;
}
}
}
point[checking_point].vis=1;
line_length+=min_distance;
checking_point=min_distance_point;
checked_point++;
}
double final_distance=sqrt((point[checking_point].x-point[0].x)*(point[checking_point].x-point[0].x)+(point[checking_point].y-point[0].y)*(point[checking_point].y-point[0].y));
line_length+=final_distance;
line_length+=2*PI*r;
printf("%.2lf\n",line_length);
return 0;
}