Thread: project Euler

Originally Posted by john.c

But I guess code is secret now.

Still brute force, and the code isn't secret, just not that well written or interesting. Here's the most interesting bit:

Code:

struct Factor {
   uint64_t factor;
   uint64_t power;
};


struct Factor_List {
   uint32_t used;
   struct Factor factors[64];  // Any more than 64 unique factors means the number is way more than 2^64

};


int main(int argc, char *argv[])
{
   find_primes(1000000000);
   struct Factor_List fl1,fl2;
   int limit = 125;
   uint64_t a = 2;
   uint64_t b = 3;
   find_factors(a/2, &fl1);  // Remove the factor of 2 from 'a'
   while(a < 1000000000) {
      int factors;
      find_factors(b, &fl2);
      factors = count_factors(&fl1,&fl2);
      if(factors > limit) {
          printf("The %ldth triangular number %ld has %d factors\n", a, a*(a+1)/2, factors);
          while(limit < factors)
             limit *= 2;
      }
      a+= 2;


      find_factors(a/2, &fl1);  // Remove the factor of 2 from 'a'
      factors = count_factors(&fl1,&fl2);
      if(factors > limit) {
          printf("The %ldth triangular number %ld has %d factors\n", b, b*(b+1)/2, factors);
          while(limit < factors)
             limit *= 2;
      }
      b+= 2;
   }
}