HDU 1232: 畅通工程(in Java)

/** * @link http://acm.hdu.edu.cn/showproblem.php?pid=1232 * @author Sycamore * @date Aug, 18 */import java.util.*;

class Main{   static int []parent=new int[1000];   static int find(int x)   {      return parent[x]=x==parent[x]?x:find(parent[x]);   }   static void Union(int x,int y)   {      parent[find(x)]=find(y);   }    public static void main(String args[]){        Scanner scanner=new Scanner(System.in);        while(scanner.hasNext())        {           int n=scanner.nextInt();           if(n==0)break;           int m=scanner.nextInt();           for(int i=1;i<=n;i++)parent[i]=i;           for(int i=0;i<m;i++)           {              int a=scanner.nextInt(),b=scanner.nextInt();            Union(a,b);           }           int cnt=0;           for(int i=1;i<=n;i++)              if(parent[i]==i)                 ++cnt;           System.out.println(cnt-1);        }        scanner.close();    }}