kruskal最小生成树，只不过在坐标系上
1 #include<iostream> 2 #include<cstdio> 3 #include<cstdlib> 4 #include<string> 5 #include<cstring> 6 #include<cmath> 7 #include<algorithm> 8 #include<ctime> 9 #include<queue> 10 #include<stack> 11 #include<map> 12 #include<set> 13 using namespace std; 14 int getint() 15 { 16 int ret=0,f=1; 17 char ch=getchar(); 18 while(ch<'0'||ch>'9') 19 { 20 if(ch=='-')f=0; 21 ch=getchar(); 22 } 23 while(ch>='0'&&ch<='9')ret*=10,ret+=ch-'0',ch=getchar(); 24 return f==0?-ret:ret; 25 } 26 struct bian 27 { 28 int x,y,v; 29 bool operator < (const bian &a)const 30 { 31 return v<a.v; 32 } 33 }bi[500050]; 34 int Max,n,m,ed,ans,tot,a[555],x[1010],y[1010],fa[1010]; 35 int find(int x) 36 { 37 return x==fa[x]?x:fa[x]=find(fa[x]); 38 } 39 int main() 40 { 41 n=getint(); 42 for(int i=1;i<=n;i++)a[i]=getint(); 43 m=getint(); 44 for(int i=1;i<=m;i++)fa[i]=i,x[i]=getint(),y[i]=getint(); 45 for(int i=1;i<=m;i++) 46 for(int j=i+1;j<=m;j++) 47 bi[++ed].x=i,bi[ed].y=j,bi[ed].v=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]); 48 sort(bi+1,bi+ed+1); 49 for(int i=1;i<=ed;i++) 50 { 51 int q=find(bi[i].x),w=find(bi[i].y); 52 if(q!=w) 53 { 54 fa[q]=w; 55 tot++; 56 if(tot==m-1) 57 { 58 Max=bi[i].v; 59 break; 60 } 61 } 62 } 63 for(int i=1;i<=n;i++)if(a[i]*a[i]>=Max)ans++; 64 printf("%d",ans); 65 return 0; 66 }