hdu 1875 畅通工程再续 最小生成树

#include<iostream>
#include<cstdio>
#include<cmath>

using namespace std;

struct edge
{
int u;
int v;
int w;
};

struct  Point
{
int x;
int y;
Point(int x=0,int y=0):x(x),y(y) {}

};

typedef  Point  Vector;

Vector operator-(Point A,Point B)
{
return Point(A.x-B.x,A.y-B.y);

}

int Length2(Point A)
{
return A.x*A.x+A.y*A.y;

}

double  Length(Point A)
{
return sqrt(A.x*A.x+A.y*A.y);
}

Point p[205];

edge e[50000];
int  fa[205];

int  find(int x) {return x==fa[x]?x:fa[x]=find(fa[x]);}
bool  edge_cmp(edge a,edge b)
{
return a.w<b.w;
}

int n,m;

int cc;
void   init()
{
for(int i=0;i<n;i++)
{
fa[i]=i;
}
cc=n;
}

double  kruskal()
{
double ans=0;
sort(e,e+m,edge_cmp);
for(int i=0;i<m;i++)
{
if(e[i].w>1000000||e[i].w<100)  continue;

int x=find(e[i].u);
int y=find(e[i].v);

if(x!=y)
{
fa[x]=y;
ans+=sqrt(e[i].w)*100;
cc--;
}
}

return ans;
}

int main()
{
int T;
cin>>T;

while(cin>>n)
{
init();

for(int i=0;i<n;i++)
{
scanf("%d%d",&p[i].x,&p[i].y);

}

int cnt=0;

for(int i=0;i<n;i++)
for(int j=i+1;j<n;j++)
{
e[cnt].u=i;
e[cnt].v=j;
e[cnt].w=Length2(p[i]-p[j]);
cnt++;
}

m=cnt;

double  ans=kruskal();
if(cc==1)
{
printf("%.1f\n",ans);
}
else{
cout<<"oh!"<<endl;
}

}

}