1389: 케빈 베이컨의 6단계 법칙

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {

	public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
	public static MyScanner sc = new MyScanner();

	static int pi(String s) {
		return Integer.parseInt(s);
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	
	static int n;
	static int bacon(int start, boolean[][] arr){
	    Queue<Integer> q = new LinkedList<>();
	    int[] visited = new int[n+1];
        for(int i=1; i<=n; i++){
            visited[i] = -1;
        }
	    visited[start] = 0;
	    q.add(start);
	    while(!q.isEmpty()){
	        int now = q.poll();
	        for(int i=1; i<=n ;i++){
	            if(arr[now][i]==true&&visited[i]==-1){
	                visited[i] = visited[now]+1;
	                q.add(i);
	            }
	        }
	    }
	    int sum = 0;
    for(int i=1; i<=n; i++){
        sum += visited[i];
    }
    return sum;
	}
	public static void main(String[] args) throws Exception {
        n = sc.nextInt();
        int m = sc.nextInt();
        boolean[][] arr = new boolean[n+1][n+1];
        for(int i=0; i<m; i++){
            int a = sc.nextInt(), b = sc.nextInt();
            arr[a][b] = true;
            arr[b][a] = true;
        }
        int[] arrr = new int[n+1];
        
        for(int i=1; i<=n; i++){
            arrr[i] = bacon(i, arr);
        }
        
        int min = 1;
        for(int i=1; i<=n; i++){
            if(arrr[i]<arrr[min]){
                min = i;
            }
        }
        out.println(min);
        out.flush();
	}
}