Poj Solution 1496

http://poj.org/problem?id=1496

//* @author: 82638882@163.com
import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System.in);
        while(in.hasNext())
        {
        String s=in.next();
        boolean bb=true;
        for(int i=0;i< s.length()-1;i++)
        {
          if(s.charAt(i)-s.charAt(i+1)>=0)
          {
            System.out.println(0);
            bb=false;
            break;
           }
        }
        if(!bb)continue;
        int l=s.length();
        long ans=0;
        for(int i=1;i< l;i++)
            ans+=find(26,i);
        int k=0;
        for(int i=0;i< l;i++)
        {
          k=0;
          if(i!=0)k=s.charAt(i-1)-'a'+1;
          int y=s.charAt(i)-'a'+1;
          for(int j=y-1;j>k;j--)
          {
            ans+=find(26-j,l-i-1);
          }
        }
        System.out.println(ans+1);
        }
    }
    public static long find(int u,long a)
    {
        if(u< a) return 0;
        if(a==0) return 1;
        long l=1;
        for(int i=u;i>u-a;i--)
            l*=i;
        for(int i=1;i<=a;i++)
            l/=i;
        return l;
    }
}
											
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