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// https://quuxplusone.github.io/blog/2019/03/06/pythagorean-triples/
#include <stdio.h>
#include <stc/coroutine.h>
void triples_vanilla(int max_c) {
for (int c = 5, i = 0;; ++c) {
for (int a = 1; a < c; ++a) {
for (int b = a + 1; b < c; ++b) {
if ((int64_t)a*a + (int64_t)b*b == (int64_t)c*c) {
if (c > max_c)
goto done;
printf("%d: {%d, %d, %d}\n", ++i, a, b, c);
}
}
}
}
done:;
}
struct triples {
int max_c;
int a, b, c;
int cco_state;
};
int triples_coro(struct triples* t) {
cco_routine(t) {
for (t->c = 5;; ++t->c) {
for (t->a = 1; t->a < t->c; ++t->a) {
for (t->b = t->a + 1; t->b < t->c; ++t->b) {
if ((int64_t)t->a * t->a +
(int64_t)t->b * t->b ==
(int64_t)t->c * t->c)
{
if (t->c > t->max_c)
cco_return;
cco_yield();
}
}
}
}
cco_cleanup:
puts("done");
}
return 0;
}
int gcd(int a, int b) {
while (b) {
int t = a % b;
a = b;
b = t;
}
return a;
}
int main(void)
{
puts("Vanilla triples:");
triples_vanilla(20);
puts("\nCoroutine triples with GCD = 1:");
struct triples t = {.max_c = 100};
int n = 0;
cco_blocking_call(triples_coro(&t)) {
if (gcd(t.a, t.b) > 1)
continue;
if (++n <= 20)
printf("%d: {%d, %d, %d}\n", n, t.a, t.b, t.c);
else
cco_stop(&t);
}
}
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