leetcode-go/poj/3278.catch-that-cow/Solution.java

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Solution {
    private static int catchCow(int N, int K) {
        boolean[] used = new boolean[100001];
        Queue<Integer> queue = new LinkedList<Integer>();
        queue.offer(N);
        used[N] = true;
        int size = queue.size();
        int cnt = 0;
        while (!queue.isEmpty()) {
            Integer i = queue.poll();
            size--;
            if (i == K) return cnt;
            if (i - 1 >= 0 && !used[i - 1]) {
                queue.offer(i - 1);
                used[i - 1] = true;
            }
            if (i + 1 <= 100000 && !used[i + 1]) {
                queue.offer(i + 1);
                used[i + 1] = true;
            }
            if (i * 2 <= 100000 && !used[i * 2]) {
                queue.offer(i * 2);
                used[i * 2] = true;
            }
            if (size == 0) {
                size = queue.size();
                cnt++;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
          int N = scanner.nextInt();
          int K = scanner.nextInt();
          System.out.println(catchCow(N, K));
        }
        scanner.close();
    }
}