pku1142 Smith Numbers

http://poj.org/problem?id=1142

数学，分解质因数

#include <stdio.h>
#include <math.h>
#define N 10000000

int a[N], b[N], tot;

int f(int x)
{
    int sum = 0;
    while(x)
    {
        sum += x%10;
        x /= 10;
    }
    return sum;
}

int factor(int n)
{
    int sum, j, temp, i, now;
    int flag = 0;
    if(n == 2)
    {
        return 0;
    }
    temp = (int) ((double)sqrt(n) + 1);
    tot = 0;
    now = n;
    for(i=2; i<=temp; i++)
    {
        if(n%i == 0)
        {
            flag = 1;
        }
        if(now%i == 0)
        {
            a[++tot] = i;
            b[tot] = 0;
            while(now%i == 0)
            {
                ++ b[tot];
                now /= i;
            }
        }
    }
    if(flag == 0)
    {
        return 0;
    }
    if(now != 1)
    {
        a[++tot] = now;
        b[tot] = 1;
    }
    sum = 0;
    for(i=1; i<=tot; i++)
    {
        sum += f(a[i])*b[i];
    }
    if(sum == f(n))
    {
        return 1;
    }
    return 0;
}

int main()
{
    int n, i;
    while(scanf("%d", &n), n)
    {
        for(i=n+1; 1; i++)
        {
            if(factor(i))
            {
                printf("%d\n", i);
                break;
            }
        }
    }
    return 0;
}