My algorithm is about Binary Search.


#include <stdio.h>
int main()
{
    float a,b,m=0;
    long n,l,l2,lf,rg,c,k;
    float m1=0,m2=0;
    FILE* fname=stdin;
    FILE* fout=stdout;
    fscanf(fname,"%f%f%ld",&a,&b,&n);
    for (l=0; l<=n; l++)
    {
        if (l>0)
            if ( (l*l)-(l-1)*(l-1) >=
a ) break;
        lf=1; rg=n-l; c=(lf+rg)/2; k=0;
        for (; lf<=rg; c=(lf+rg)/2)
        {
            if ( (c*c)-(c-1)*(c-1) <
b )
            { k=c; lf=c+1; }
            else rg=c-1;
        }
        if ( (l*a)+(k*b) - (l*l+k*k) > m )
        {
            m=(l*a)+(k*b) -
(l*l+k*k);
            m1=l; m2=k;
        }
    }
    m=(m1*a)+(m2*b) - (m1*m1+m2*m2);
    if (m==0) m=0;
    fprintf(fout,"%.2f\n%.0f %.0f\n",m,m1,m2);
    fclose(fname); fclose(fout);
    return 0;
}