void *look_for_min(void *threadid){
long tid;
tid = (long) threadid;
long start, end;
long j, k;
start = tid*M/NUM_THREADS + 1;
end = start + M/NUM_THREADS -1;
for(j=start; j<end; j++){
long sum = 0, differences = 0;
for(k=j+1; k<M; k++){
sum = formula(j) + formula(k);
differences = formula(k) - formula(j);
if(is_pentagonal(sum) && is_pentagonal(differences))
if(sum - differences <= minD){
pthread_mutex_lock(&mutex1);
minD = sum - differences;
pthread_mutex_unlock(&mutex1);
}
}
//printf("%d\n", formula(i));
}
printf("%d\n", minD);
pthread_exit(NULL);
}
void fn0() {
std::vector<int> nums { 1 };
for (int i = 2; ; i++) {
int pk = pn(i);
for (int pj: nums) {
if (is_pentagonal(pj + pk) && is_pentagonal(pk - pj)) {
std::cout << std::abs(pk - pj) << std::endl;
return;
}
}
nums.push_back(pk);
}
}
int main() {
int i, j;
int vi, vj;
for (i=2;;++i)
for (j=1;j<i;++j) {
vi = (i * (3*i-1)) / 2;
vj = (j * (3*j-1)) / 2;
if (is_pentagonal(vi+vj) && is_pentagonal(vi-vj)) {
printf("%d\n", vi-vj);
return 0;
}
}
return 0;
}
int main(void){
clock_t ini = clock();
for(int k = 286; !ans; ++k){
long long a = k, x = 2 * a * a - a;
if(is_pentagonal(x) && is_triangle(x)) ans = x;
}
printf("Time spent: %.3lfs\n", ((double)(clock() - ini))/CLOCKS_PER_SEC);
printf("Answer: %lld\n", ans);
return 0;
}
/* this program may take a few seconds */
int main(void)
{
unsigned i, j;
unsigned min = UINT_MAX;
for (i = 1; i < N; i++) {
for (j = i; j < N; j++) {
unsigned k = pentagonal(i);
unsigned l = pentagonal(j);
if (is_pentagonal(k+l) && is_pentagonal(l-k)) {
if (l-k < min) {
min = l-k;
}
}
}
}
printf("%u\n", min);
return 0;
}
// test if is_triangle always returns expected results
// as i'm always weary when working with floating points
void test_is_pentagonal() {
for (int n = 1; n < 100000; n++) {
int x = pn(n);
if (x < 0) {
break; // we've gone too far!
}
if (!is_pentagonal(x)) {
std::cout << "FAILED TEST: " << x << " is t" << n << " but returned not pentagonal" << std::endl;
}
}
}
int print_properties_num(longnum num)
{
printf("%llu:\nprime factors: ", num);
print_prime_factors(num);
printf("\n");
if ( is_abundant(num) ) printf(" abundant");
if ( is_amicable(num) ) printf(" amicable");
if ( is_apocalyptic_power(num) ) printf(" apocalyptic_power");
if ( is_aspiring(num) ) printf(" aspiring");
if ( is_automorphic(num) ) printf(" automorphic");
if ( is_cake(num) ) printf(" cake");
if ( is_carmichael(num) ) printf(" carmichael");
if ( is_catalan(num) ) printf(" catalan");
if ( is_composite(num) ) printf(" composite");
if ( is_compositorial(num) ) printf(" compositorial");
if ( is_cube(num) ) printf(" cube");
if ( is_deficient(num) ) printf(" deficient");
if ( is_easy_to_remember(num) ) printf(" easy_to_remember");
if ( is_ecci1(num) ) printf(" ecci1");
if ( is_ecci2(num) ) printf(" ecci2");
if ( is_even(num) ) printf(" even");
if ( is_evil(num) ) printf(" evil");
if ( is_factorial(num) ) printf(" factorial");
if ( is_fermat(num) ) printf(" fermat");
if ( is_fibonacci(num) ) printf(" fibonacci");
if ( is_google(num) ) printf(" google");
if ( is_happy(num) ) printf(" happy");
if ( is_hungry(num) ) printf(" hungry");
if ( is_hypotenuse(num) ) printf(" hypotenuse");
if ( is_lazy_caterer(num) ) printf(" lazy_caterer");
if ( is_lucky(num) ) printf(" lucky");
if ( is_mersenne_prime(num) ) printf(" mersenne_prime");
if ( is_mersenne(num) ) printf(" mersenne");
if ( is_narcissistic(num) ) printf(" narcissistic");
if ( is_odd(num) ) printf(" odd");
if ( is_odious(num) ) printf(" odious");
if ( is_palindrome(num) ) printf(" palindrome");
if ( is_palindromic_prime(num) ) printf(" palindromic_prime");
if ( is_parasite(num) ) printf(" parasite");
if ( is_pentagonal(num) ) printf(" pentagonal");
if ( is_perfect(num) ) printf(" perfect");
if ( is_persistent(num) ) printf(" persistent");
if ( is_power_of_2(num) ) printf(" power_of_2");
if ( is_powerful(num) ) printf(" powerful");
if ( is_practical(num) ) printf(" practical");
if ( is_prime(num) ) printf(" prime");
if ( is_primorial(num) ) printf(" primorial");
if ( is_product_perfect(num) ) printf(" product_perfect");
if ( is_pronic(num) ) printf(" pronic");
if ( is_repdigit(num) ) printf(" repdigit");
if ( is_repunit(num) ) printf(" repunit");
if ( is_smith(num) ) printf(" smith");
if ( is_sociable(num) ) printf(" sociable");
if ( is_square_free(num) ) printf(" square_free");
if ( is_square(num) ) printf(" square");
if ( is_tetrahedral(num) ) printf(" tetrahedral");
if ( is_triangular(num) ) printf(" triangular");
if ( is_twin(num) ) printf(" twin");
if ( is_ulam(num) ) printf(" ulam");
if ( is_undulating(num) ) printf(" undulating");
if ( is_untouchable(num) ) printf(" untouchable");
if ( is_vampire(num) ) printf(" vampire");
if ( is_weird(num) ) printf(" weird");
printf("\n\n");
return 0;
}
