int prIsPrime(VMGlobals *g, int numArgsPushed)
{
PyrSlot *a;
int n, p, sqrtn, i;
a = g->sp;
n = slotRawInt(a);
SetNil(a);
if (n <= 2) {
if (n == 2) { SetTrue(a); }
else { SetFalse(a); }
} else if (n <= nthPrime(NUMPRIMES-1)) {
// do a search of the primes table
i = findPrime(n);
if (i >= 0) { SetTrue(a); }
else { SetFalse(a); }
} else {
#ifdef SC_WIN32
sqrtn = (int)sqrt(static_cast<double>(n));
#else
sqrtn = (int)sqrt(n);
#endif
for (i=0; i<NUMPRIMES; ++i) {
p = nthPrime(i);
if (n % p == 0) { SetFalse(a); break; }
if (p >= sqrtn) { SetTrue(a); break; }
}
}
return errNone;
}
int main(void)
{
int result = nthPrime(10000);
printf("%d\n", result);
return result;
// Answer: 104743
}
long nextPrime(int n)
{
// binary search of primes table
int i, p, lo = 0, hi = NUMPRIMES-1;
while (hi>=lo) {
i = (lo + hi) >> 1;
p = nthPrime(i);
if (n==p) return i;
if (n<p) hi = i - 1;
else lo = i + 1;
}
return sc_clip(lo, 0, NUMPRIMES-1);
}
long findPrime(int n)
{
// binary search of primes table
int i, p, lo = 0, hi = NUMPRIMES-1;
while (hi>=lo) {
i = (lo + hi) >> 1;
p = (int)nthPrime(i); // kengo:
if (n==p) return i;
if (n<p) hi = i - 1;
else lo = i + 1;
}
return -1;
}
int prNthPrime(VMGlobals *g, int numArgsPushed)
{
PyrSlot *a;
int n, p;
a = g->sp;
n = slotRawInt(a);
p = nthPrime(n);
if (p == 0) {
SetNil(a);
} else {
SetInt(a, p);
}
return errNone;
}
int prIndexOfPrime(VMGlobals *g, int numArgsPushed)
{
PyrSlot *a;
int n, p;
a = g->sp;
n = slotRawInt(a);
if (n <= 2) {
if (n == 2) { SetInt(a, 0); }
else { SetNil(a); }
} else if (n <= nthPrime(NUMPRIMES-1)) {
p = findPrime(n);
if (p < 0) {
SetNil(a);
} else {
SetInt(a, p);
}
} else {
SetNil(a);
}
return errNone;
}
uint64_t PrimeSieve::nthPrime(uint64_t n)
{
return nthPrime(0, n);
}
ProblemInteger run(void) {
return nthPrime(10001);
}
ProblemInteger check(void) {
return nthPrime(6);
}