日期:2014-05-20 浏览次数:20823 次
import java.math.BigInteger;
import java.util.Arrays;
public class da2 {
static BigInteger[] table = new BigInteger[10];
static BigInteger sum = BigInteger.ZERO;
static int times = 0;
static BigInteger MAX = BigInteger.TEN.pow(21).subtract(BigInteger.ONE);
static BigInteger MIN = BigInteger.TEN.pow(21 - 1);
public static void main(String[] args) {
long time = System.nanoTime();
int n = 21;
int[] nums = new int[n];
for (int i = 0; i < 10; i++)
table[i] = BigInteger.valueOf(i).pow(n);
f(0,n,nums,0);
time = System.nanoTime() - time;
System.out.println("计算时间:"+time / 1000000000.0 + "秒");
System.out.println("循环次数:"+times+"次");
}
public static void f(int i,int n,int[] nums,int m)
{
if(i > n - 1)
{
times++;
if(panduan(nums))
System.out.println(sum);
}
else
{
for(int v = m;v < 10;v++)
{
nums[i] = v;
sum = sum.add(table[v]);
f(i+1,n,nums,v);
sum = sum.subtract(table[v]);
}
}
}
public static boolean panduan(int[] nums)
{
if(sum.compareTo(MAX)>0||sum.compareTo(MIN)<0)
return false;
String s = String.valueOf(sum);
int length = s.length();
int[] a = new int[length];
for (int i = 0; i < length; i++)
a[i] = s.charAt(i) - '0';
int[] b = nums.clone();
Arrays.sort(a);
Arrays.sort(b);
return Arrays.equals(a, b);
}
}