A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 * 99.
Find the largest palindrome made from the product of two 3-digit numbers.
2个两位数相乘得到的最大的回文数是9009，如：9009=91*99。
找出2个3位数相乘得到的最大的回文数。
static void Main(string[] args)
{
Int64 i, j,k,m;
for (i = 999 * 999; i >= 100 * 100; i--)
{
if (isPrime(i) == true)
{
for (j = 999; j >= 100; j--)
{
k = i % j;
m = i / j;
if (k == 0 && (m >= 100 && m <= 999))
{
Console.WriteLine("{0}*{1}={2}",j,m,i);
Console.ReadLine();
return;
}
}
}
}
}
public static bool isPrime(Int64 a)
{
char[] n = new char[20];
int i,k=0;
while(a>0)
{
n[k++] = (char)(a%10);
a=a/10;
}
for(i =0;i<k/2;i++)
{
if(n[i]!=n[k-i-1]) return false;
}
return true;
}
结果：993*913=906609
