[ACM] hdu 2717 Catch That Cow (BFS)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2717

参考链接：http://blog.csdn.net/sr_19930829/article/details/26398223

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


public class Main {
	
	static int N,K;
	static int len=100000;
	static int[] hash = new int[len+10];
	static boolean[] vis = new boolean[len+10];
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		N = sc.nextInt();
		K = sc.nextInt();
		if(N==K){
			System.out.println(0);
		}else
		{
			bfs();
			System.out.println(hash[K]);
		}

	}

	private static void bfs() {
		// TODO Auto-generated method stub
			Queue<node> queue = new LinkedList<node>();
			node n = new node(N);
			queue.offer(n);
			vis[N] = true;
			hash[N] = 0;
			while(!queue.isEmpty()){
				node temp = queue.poll(); //queue.poll() 获取并移除队头
				int num = temp.getNum();
				if(num+1==K||num-1==K||num*2==K){//找到
					hash[K]=hash[num]+1;
					break;
				}
				if(num-1>=0&&!vis[num-1]){
					node m = new node(num-1);
					queue.offer(m);
					vis[num-1]=true;
					hash[num-1]=hash[num]+1;
				}
				if(num+1<=len&&!vis[num+1]){
					node m = new node(num+1);
					queue.offer(m);
					vis[num+1] = true;
					hash[num+1] = hash[num]+1;
				}
				if(num*2<=len&&!vis[num*2]){
					node m = new node(num*2);
					queue.offer(m);
					vis[num*2]=true;
					hash[num*2]=hash[num]+1;
				}
			}
			
			
		
		
		
	}
	
	public  static class node{
		int num;
		public node(int num){
			this.num = num;
		}
		public int getNum() {
			return num;
		}
		public void setNum(int num) {
			this.num = num;
		}
		
	}

	
}

　　没有AC不知道为什么。