用java简单实现农夫、狼、羊和菜过河的问题

用java简单实现农夫、狼、羊和菜过河的问题

题目描述： 有一个农夫带一只羊、一筐菜和一只狼过河， 如果没有农夫看管，则狼要吃羊，羊要吃菜， 但是船很小，只够农夫带一样东西过河。 问农夫该如何解此难题？

代码如下：

package Demo;

import java.util.ArrayList;
import java.util.List;

public class CrossRiver {
		List<String> listThis = new ArrayList<String>();
		List<String> listThat = new ArrayList<String>();
		public  CrossRiver() {
	        listThis.add("狼");
	        listThis.add("草");
	        listThis.add("羊");
	    }
		public boolean isSafe(List< String > list){
			if(list.contains("狼")&&list.contains("羊")||list.contains("羊")&&list.contains("草")){
	            return false;
	        }else{
	            return true;
	        }
		}
		public void thisTothat(){
	        String str = listThis.get(0);
	        listThis.remove(str);
	        if(this.isSafe(listThis)){
	            System.out.println("农夫带着 " + str + " 从此岸到彼岸");
	            System.out.println("此岸" + listThis + "," + "彼岸" + listThat);
	            System.out.println();
	            listThat.add(str);
	            thatToThis();
	        }else{
	            listThis.add(str);
	            thisTothat();
	        }
	    }
	    public void thatToThis(){
	        if(listThis.isEmpty()){
	            System.out.println("此岸" + listThis + "," + "彼岸" + listThat);
	            return;
	        }
	        if(isSafe(listThat)){
	            System.out.println("农夫从彼岸到此岸");
	            System.out.println("此岸" + listThis + "," + "彼岸" + listThat);
	            System.out.println();
	            thisTothat();
	        }else{
	            String str = listThat.get(0);
	            listThat.remove(0);
	            if(isSafe(listThat)){
	                System.out.println("农夫带着 " + str + " 从彼岸到此岸");
	                System.out.println("此岸" + listThis + "," + "彼岸" + listThat);
	                System.out.println();
	                listThis.add(str);
	                thisTothat();
	            }else{
	                listThat.add(str);
	                thatToThis();
	            }
	        }
	    }
	    public static void main(String[] args){
	        System.out.println("测试结果为：");
	        System.out.println();
	        new CrossRiver().thisTothat();
	    }
}

测试结果：