BZOJ2429: [HAOI2006]聪明的猴子

题目：http://www.lydsy.com/JudgeOnline/problem.php?id=2429

题解：从某一点遍历n个点，且使最长边最短，就是MST了。

代码：

 #include<cstdio>

 #include<cstdlib>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 #include<iostream>

 #include<vector>

 #include<map>

 #include<set>

 #include<queue>

 #include<string>

 #define inf 1000000000

 #define maxn 1000+5

 #define maxm 200000+5

 #define eps 1e-10

 #define ll long long

 #define pa pair<int,int>

 #define for0(i,n) for(int i=0;i<=(n);i++)

 #define for1(i,n) for(int i=1;i<=(n);i++)

 #define for2(i,x,y) for(int i=(x);i<=(y);i++)

 #define for3(i,x,y) for(int i=(x);i>=(y);i--)

 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)

 #define for5(n,m) for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)

 #define mod 1000000007
 #define sqr(x) (x)*(x)

 using namespace std;

 inline int read()

 {

     int x=,f=;char ch=getchar();

     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}

     while(ch>=''&&ch<=''){x=*x+ch-'';ch=getchar();}

     return x*f;

 }
 int n,m;
 double mx,b[maxn],d[maxn];
 bool v[maxn];
 struct rec{int x,y;}a[maxn];
 priority_queue<pa,vector<pa>,greater<pa> >q;
 inline double dist(int x,int y){return sqrt(sqr(a[x].x-a[y].x)+sqr(a[x].y-a[y].y));}
 inline void prim()
 {
     for1(i,n)d[i]=inf;
     d[]=;
     q.push(pa(,));
     while(!q.empty())
     {
         int x=q.top().second;q.pop();
         if(v[x])continue;v[x]=;
         if(d[x]>mx)mx=d[x];
         for1(i,n)if(!v[i]&&dist(i,x)<d[i])
         {
            d[i]=dist(i,x);
            q.push(pa(d[i],i));
         }
     }
 }

 int main()

 {

     freopen("input.txt","r",stdin);

     freopen("output.txt","w",stdout);

     m=read();
     for1(i,m)b[i]=read();
     n=read();
     for1(i,n)a[i].x=read(),a[i].y=read();
     prim();
     int ans=;
     for1(i,m)if(b[i]>=mx)ans++;
     cout<<ans<<endl;

     return ;

 }