백준 17204 java

목표 : 그래프 탐색 이론(DFS, BFS), 위상정렬, 플로이드 워셜, 자바스크립트, 파이썬...................

import java.util.Scanner;
import java.util.Vector;

public class bj17204 {
    static int N;
    static int K;
    static Vector<Integer> data;
    static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        inputData();
        findAnswer();
    }

    public static void inputData()
    {
        int i, num;

        data = new Vector<>();
        N = scanner.nextInt();
        K = scanner.nextInt();
        for(i = 0; i < N; i++)
        {
            num = scanner.nextInt();
            data.add(num);
        }

//        System.out.println("입력결과");
//        for(int temp : data)
//        {
//            System.out.print(temp + " ");
//        }
    }

    public static void findAnswer()
    {
        //System.out.println("\nfindAnswer");
        boolean [] visited = new boolean[N];
        int count = 0;
        int current = 0;

        while(!visited[current])
        {
            if(current == K)
            {
                System.out.println(count);
                return;
            }
            visited[current] = true;
            current = data.get(current);
            count++;
            //System.out.println("count : " + count + " / current : " + current);
        }
        System.out.println("-1");
    }
}