rq475 最大约数和

rq475 最大约数和

#include < cstdio >
#include < cstring >
#include < cmath >
using   namespace  std;

int  N;
int  a[ 1001 ];
int  f[ 1001 ] = { 0 };
int  make( int  s)
{
     int  sum = 1 ,l = sqrt( double (s));
     for ( int  i = 2 ;i <= l; ++ i)
         if (s % i == 0 ) sum = sum + i + s / i;
     if (l * l == s) sum -= l;
     return  sum;
}
int  main()
{
    scanf( " %d " , & N);
     for ( int  i = 1 ;i <= N; ++ i)
        a[i] = make(i);
     for ( int  i = 1 ;i <= N; ++ i)
         for ( int  j = N;j >= i; -- j)
             if (f[j] < f[j - i] + a[i])
                f[j] = f[j - i] + a[i];
    printf( " %d\n " ,f[N]);
     return   0 ;
}