NYOJ题目20吝啬的国度

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        
        Scanner sc=new Scanner(System.in);
        int times=sc.nextInt();
        while(times-->0){
            int n=sc.nextInt();
            int s=sc.nextInt()-1;
            
            tree=new ArrayList[n];
            for(int i=0;i<tree.length;i++) tree[i]=new ArrayList();
            visited=new boolean[n];
            must=new int[n];
            
            for(int i=1;i<n;i++){
                int v=sc.nextInt()-1;
                int u=sc.nextInt()-1;
                tree[v].add(u);
                tree[u].add(v);
            }
            
            must[s]=-1;
            dfs(s);
            
            for(int i=0;i<must.length;i++){
                System.out.print(must[i]+" ");
            }
            System.out.println();
        }
        
    }
    
    private static List<Integer> tree[];
    private static boolean visited[];
    private static int must[];
    
    public static void dfs(int i){
        visited[i]=true;
        for(Integer next:tree[i]){
            if(visited[next]) continue;
            must[next]=i+1;
            dfs(next);
        }
    }
    
}