java编程思想的一道题（吸血鬼数字）

public class Test {


	public void vampireNumber() {
		for (int i = 10; i < 100; i++) {
			for (int j = 10; j < 100; j++) {
				int product = i * j;
				if (product > 1000 && product < 10000 && product % 100 != 0 && isEqual(product, i, j)) {
					System.out.println(product + "=" + i + "*" + j);
				}
			}
		}
	}


}

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.CollectionUtils;

public class test {
	public static void main(String args[]) {
		for(int x=10;x<100;x++){
			for(int y=10;y<100;y++){
				if(chen(x,y)){//如果是魔鬼数的话则打印出来,同时把这对相乘的数也打印出来
					System.out.println(x*y+"="+x+"*"+y);
				}
			}
		}
	}

	/**
	 * 判断x,y的乘积是否是魔鬼数
	 * @param x
	 * @param y
	 * @return
	 */
	public static boolean chen(int x, int y) {
		int z = x * y;
		String s = String.valueOf(z);
		if (s.length() == 4) {
			String a = String.valueOf(s.charAt(0));
			String b = String.valueOf(s.charAt(1));
			String c = String.valueOf(s.charAt(2));
			String d = String.valueOf(s.charAt(3));
			Map<String,String> list = zuhe(a,b,c,d);
			return isHeshi(x,y,list);
		}
		return false;
	}

	/**
	 * 这个4位数的乘积可以组合成多少种2位数配对的组合
	 * 
	 * @param a
	 * @param b
	 * @param c
	 * @param d
	 * @return
	 */
	public static Map<String,String> zuhe(String a, String b, String c, String d) {
		List<String> l = new ArrayList<String>();
		l.add(a);
		l.add(b);
		l.add(c);
		l.add(d);
		
		Map<String,String> list = new HashMap<String,String>();
		for (String dd : l) {
			List<String> ll = new ArrayList<String>();
			ll.add(dd);
			Collection<String> cc = CollectionUtils.subtract(l, ll);
			for (String e : cc) {
				List<String> lll = new ArrayList<String>();
				lll.add(dd);lll.add(e);
				Collection<String> ccc = CollectionUtils.subtract(l, lll);
				String o ="";
				for(String g:ccc){
					o=o+g;
				}
				list.put(dd+e, o);
			}
		}	
		
		return list;
	}

	/**
	 * 判断原始相乘的一对数是否在排列组合后的2位数的组合中,如果是的话,那么这 对数相乘后的数字就是魔鬼数字
	 * 
	 * @param x
	 *            原始相乘的数x
	 * @param y
	 *            原始相乘的数y
	 * @param l
	 *           这个4位数的乘积可以组合成多少种2位数配对的组合
	 * @return
	 */
	public static boolean isHeshi(int x, int y, Map l) {
		String s = String.valueOf(x);
		String s2 = String.valueOf(y);
		if (l.get(s)!=null && l.get(s).equals(s2)){
			return true;
		}
		return false;
	}
}

	void findNum()
	{
		for(int i = 10 ;i<100;i++)
		{
			for(int j = i ;j <100 ;j++)
			{
				if(equ(i,j))
				{
					System.out.printf("%d * %d = %d",i,j,i*j).println();					
				}
			}			
		}		
	}
	boolean equ(int i1 , int i2)
	{
		String strResult = Integer.valueOf(i1*i2).toString();
		String strI1 = Integer.valueOf(i1).toString();
		String strI2 = Integer.valueOf(i2).toString();
		int tmpLen = strResult.length();
		for(int i = 0;i<tmpLen;i++)
		{
			String tmpStr = strResult.substring(i, i+1);	
			int index1 = strI1.indexOf(tmpStr);
			int index2 = strI2.indexOf(tmpStr);
			if( index1 ==-1 && index2 ==-1 )
				break;
			if(index1 != -1)
				strI1 = strI1.substring(0,index1) + strI1.substring(index1+1);
			else
				strI2 = strI2.substring(0,index2) + strI2.substring(index2+1);
		}
		if(strI1.equals("")&&strI2.equals(""))
			return true;			
		else 
			return false;
	}

	public static void solution1 () {
		for (int i=1000;i<9999;i++) {
			int a = i/1000;
			int b = i%1000/100;
			int c = i%100/10;
			int d = i%10;

			if (i == (a*10 + b)*(c*10 + d)) {
				System.out.println(i + " = " + a + b + " * " + c + d);
			} else if (i == (a*10 + b)*(d*10 + c)) {
				System.out.println(i + " = " + a + b + " * " + d + c);				
			} else if (i == (b*10 + a)*(c*10 + d)) {
				System.out.println(i + " = " + b + a + " * " + c + d);				
			} else if (i == (b*10 + a)*(d*10 + c)) {
				System.out.println(i + " = " + b + a + " * " + d + c);			
			} else if (i == (a*10 + c)*(b*10 + d)) {
				System.out.println(i + " = " + a + c + " * " + b + d);			
			} else if (i == (a*10 + c)*(d*10 + b)) {
				System.out.println(i + " = " + a + c + " * " + d + d);		
			} else if (i == (c*10 + a)*(b*10 + d)) {
				System.out.println(i + " = " + c + a + " * " + b + d);		
			} else if (i == (c*10 + a)*(d*10 + b)) {
				System.out.println(i + " = " + c + a + " * " + d + b);		
			} else if (i == (a*10 + d)*(c*10 + b)) {
				System.out.println(i + " = " + a + d + " * " + c + b);
			} else if (i == (a*10 + d)*(b*10 + c)) {
				System.out.println(i + " = " + a + d + " * " + b + c);
			} else if (i == (d*10 + a)*(c*10 + b)) {
				System.out.println(i + " = " + d + a + " * " + c + b);
			} else if (i == (d*10 + a)*(b*10 + c)) {
				System.out.println(i + " = " + d + a + " * " + b + c);
			}
		}
	}