#include <io.h>
#include <stdio.h>
#include <time.h>

#define MAX_R 20

unsigned short int valid(unsigned short int*p, unsigned short int r);
void calc_next_pow(unsigned short int*p);

int main()
{FILE *end1;int bignum = 500;int rot; int a;
time_t timer;
unsigned short int pow_two[MAX_R];
unsigned long int power=0;
int z;unsigned short int r;
end1 = fopen("answer.dat","a");
for (z=0;z<(MAX_R-1);z++)pow_two[z]=0;
pow_two[MAX_R-1]=1;
for (r=1;r<=MAX_R;r++)
        {while (!valid(pow_two,r))
                {if(power>=89)
                   {power += bignum;
                   rot = bignum;
                   }
                else
                   {power++;
                   rot = 1;
                   }
                a=1;
                do
                    {calc_next_pow(pow_two);
                     a += 1;
                }
                while (a<=rot);
                }
        time(&timer);
        printf("r = %hd  Power of 2 is %ld   %s",r,power,ctime(&timer));
        fprintf(end1,"r = %hd  Power of 2 is %ld   %s",r,power,ctime(&timer));
        }
return(0);
}

unsigned short int valid(unsigned short int*p, unsigned short int r)
{int i;
for(i=MAX_R-r;i<MAX_R;i++)
        if(p[i]!=1 && p[i]!=2)
                return(0);
return(1);
}

void calc_next_pow(unsigned short int*p)
{unsigned short int carry=0; int i;
for (i=MAX_R-1;i>=0;i--)
        {p[i]+=p[i]+carry;
        if (p[i]>9)
                {p[i]-=10;
                carry=1;
                }
        else carry=0;
        }
}