전력망을 둘로 나누기

https://school.programmers.co.kr/learn/courses/30/lessons/86971

import java.util.*;

class Solution {
    public int solution(int n, int[][] wires) {
        
        ArrayList<ArrayList<Integer>> map = new ArrayList<ArrayList<Integer>>();
        for(int i = 0; i < n+1; ++i)
            map.add(new ArrayList<Integer>());
        
        for(int i = 0; i < wires.length; ++i)
        {
            int a = wires[i][0];
            int b = wires[i][1];
            
            map.get(a).add(b);
            map.get(b).add(a);
        }
        
        int answer = 1000000;
        for(int i = 0; i < wires.length; ++i)
        {
            int a = wires[i][0];
            int b = wires[i][1]; 
            
            int acount = bfs(a, n, map, b);
            int bcount = bfs(b, n, map, a);
            answer = Math.min(answer, Math.abs(acount-bcount));
        }
        
        
        
        return answer;
    }
    
    public int bfs(int start, int n, ArrayList<ArrayList<Integer>> map, int cut)
    {
        int count = 1;
        
        Queue<Integer> que = new LinkedList<Integer>();
        
        boolean[] visit = new boolean[n+1];
        que.add(start);
        visit[start] = true;
        
        while(que.isEmpty()==false)
        {
            ArrayList<Integer> cur = map.get(que.poll());
            
            for(int nei : cur)
            {
               
                if(nei == cut)
                    continue;
                if(visit[nei])
                    continue;
                
                visit[nei] = true;
                que.add(nei);
                count++;
            }
        }
        return count;
    }
}