hdu 1333 Smith Numbers（暴力思路）

题目：http://acm.hdu.edu.cn/showproblem.php?pid=1333

Smith Numbers

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 1734    Accepted Submission(s): 567

Problem Description

While skimming his phone directory in 1982, Albert Wilansky, a mathematician of Lehigh University, noticed that the telephone number of his brother-in-law H. Smith had the following peculiar property: The sum of the digits of that number was equal to the sum of the digits of the prime factors of that number. Got it? Smith’s telephone number was 493-7775. This number can be written as the product of its prime factors in the following way:

4937775 = 3 * 5 * 5 * 65837
The sum of all digits of the telephone number is 4+9+3+7+7+7+5= 42?, and the sum of the digits of its prime factors is equally 3+5+5+6+5+8+3+7= 42. Wilansky was so amazed by his discovery that he named this kind of numbers after his brother-in-law: Smith numbers.

As this observation is also true for every prime number, Wilansky decided later that a (simple and unsophisticated) prime number is not worth being a Smith number, so he excluded them from the definition.

Wilansky published an article about Smith numbers in the Two Year College Mathematics Journal and was able to present a whole collection of different Smith numbers: For example, 9985 is a Smith number and so is 6036. However,Wilansky was not able to find a Smith number that was larger than the telephone number of his brother-in-law. It is your task to find Smith numbers that are larger than 4937775!

 

Input

The input consists of a sequence of positive integers, one integer per line. Each integer will have at most 8 digits. The input is terminated by a line containing the number 0.

 

Output

For every number n > 0 in the input, you are to compute the smallest Smith number which is larger than n, and print it on a line by itself. You can assume that such a number exists.

 

Sample Input

   
   
   
   

    
    
    
    4937774
0
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    4937775 
   
   
   
   

分析：
smith number：除素数外，所有位的数的和等于该数字的所有素因子的所有位上的数字的和。
输入的数字是最多8位，int不是最多10位吗？估摸着用int应该没有问题。就是一个数字一个数字的试。

import java.util.*;
public class Main {
    static int getsum(int x){
        int ans=0;
        while(x>0){
            ans=ans+x%10;
            x/=10;
        }
        return ans;
    }
    static final int maxn=(int)(1e4+10);
    static int[] fac=new int [maxn],pow=new int [maxn];
    static int cnt;
    static void resolve(int x){
        cnt=0;
        Arrays.fill(pow,0);
        for(int i=2;i*i<=x;i++){
            if(x%i==0){
                fac[cnt]=i;
                while(x%i==0){
                    x/=i;
                    pow[cnt]++;
                }
                cnt++;
            }
        }
        if(x>1){
            fac[cnt]=x;
            pow[cnt++]++;
        }
    }
    public static void main(String[] args) {
        int n,k,sum1,sum2;
        Scanner sc=new Scanner(System.in);
        while(sc.hasNextInt()){
            n=sc.nextInt();
            if(n==0) break;
            k=n+1;
            while(k>n){
                resolve(k);
                if(fac[0]==k){
                    k++;
                    continue;
                }
                sum2=0;
                for(int i=0;i<cnt;i++){
                    sum2+=getsum(fac[i])*pow[i];
                }
                sum1=getsum(k);
                if(sum1==sum2) break;
                k++;
            }
            System.out.println(k);
        }
    }

}