[백준] BOJ - 2644 촌수계산 java (실버2)

https://www.acmicpc.net/problem/2644

2644번: 촌수계산

 

 

나의풀이

import java.util.*;
import java.io.*;
public class Main {
    static List<Integer>[] family;
    static boolean[] visited;
    static int answer=-1;
    public static void dfs(int a, int b, int cost){
        if(a==b){
            answer=cost;   
        }
        visited[a]=true;
        for(int i=0; i<family[a].size(); i++){
            int temp=family[a].get(i);
            if(visited[temp] == false){
                dfs(temp, b, cost+1);
            }
        }
    }
    
    public static void main(String args[]) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(br.readLine());

        int n = Integer.parseInt(st.nextToken()); //전체 사람의 수
        family= new ArrayList[n+1];
        visited= new boolean[n+1];
        
        for(int i=0; i<=n; i++){
            family[i]= new ArrayList<>();
        }
        
        st = new StringTokenizer(br.readLine());
        int a = Integer.parseInt(st.nextToken());//사람 a
        int b = Integer.parseInt(st.nextToken());//사람 b
        st = new StringTokenizer(br.readLine());
        int m= Integer.parseInt(st.nextToken());//관계의 개수
        
        for(int i=0; i<m; i++){
            st = new StringTokenizer(br.readLine());
            int x = Integer.parseInt(st.nextToken());
            int y = Integer.parseInt(st.nextToken());
            family[x].add(y);
            family[y].add(x);
        }
        dfs(a,b,0);
        bw.write(Integer.toString(answer));
        
        bw.flush();
        br.close();
        bw.close();
        
        
    }
}