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// https://quuxplusone.github.io/blog/2019/03/06/pythagorean-triples/
#include <stc/algo/coroutine.h>
#include <stdio.h>
void triples_vanilla(int n) {
for (int c = 5; n; ++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) {
printf("{%d, %d, %d}\n", a, b, c);
if (--n == 0) goto done;
}
}
}
}
done:;
}
struct triples {
int n;
int a, b, c;
int cco_state;
};
bool triples_next(struct triples* I) {
cco_begin(I);
for (I->c = 5; I->n; ++I->c) {
for (I->a = 1; I->a < I->c; ++I->a) {
for (I->b = I->a + 1; I->b < I->c; ++I->b) {
if ((int64_t)I->a*I->a + (int64_t)I->b*I->b == (int64_t)I->c*I->c) {
cco_yield(true);
if (--I->n == 0) cco_return;
}
}
}
}
cco_final:
puts("done");
cco_end(false);
}
int gcd(int a, int b) {
while (b) {
int t = a % b;
a = b;
b = t;
}
return a;
}
int main()
{
puts("Vanilla triples:");
triples_vanilla(6);
puts("\nCoroutine triples:");
struct triples t = {INT32_MAX};
int n = 0;
while (triples_next(&t)) {
if (gcd(t.a, t.b) > 1)
continue;
if (t.c < 100)
printf("%d: {%d, %d, %d}\n", ++n, t.a, t.b, t.c);
else
cco_stop(&t);
}
}
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