UVA 10483 - The Sum Equals the Product

Problem link

Keyword: precalculation, math

Algorithm:

Um... I couldn't come up with a good solution, so I tried precalculation as the solution.
There's not many solutions to this problem, so we can use some code to generate the code to be submitted.
Here's my code for calculation.

Code:

#include<cstdio>
bool p( int *prime, int n )
{
    for( int i = 0; prime[ i ] * prime[ i ] <= n; ++i )
        if( n % prime[ i ] == 0 )
            return false;
    return true;
}

int main()
{
    int a, b, c, d, r, prime[ 2820 ] = { 2 }, all = 0;
    bool isprime[ 25600 ] = { false, true, true };
    for( int i = 3; i < 25600; i += 2 )
        if( p( prime, i ) )
            prime[ ++all ] = i, isprime[ i ] = true;
    all = 0;
    freopen("test","r",stdin);

    while( scanf( "%d.%d %d.%d", &a, &b, &c, &d ) != EOF )
    {
        int low = a*100 + b, high = c*100 + d;
        for( int i = low; i <= high; ++i )
            if( !isprime[ i ] )
                for( int p = 1; p < i && p*p*p <= i * 10000; ++p )
                    if( i * 10000 % p == 0 )
                        for( int q = p; p*q*q <= i*10000; ++q )
                            if( i*10000/p % q == 0 )
                            {
                                r = i * 10000 / p / q;
                                if( p + q + r == i && p * q * r == i*10000 )
                                    printf( "sum[ %d ] = %d, a[ %d ] = %d, b[ %d ] = %d, c[ %d ] = %d;\n", all, i, all, p, all, q, all, r ), ++all;
                            }
    }
    return 0;
}