Factors join(const Factors & lhs, const Factors & rhs) {
Factors retval;
retval.reserve(lhs.size() + rhs.size());
retval.insert(std::end(retval), std::begin(lhs), std::end(lhs));
retval.insert(std::end(retval), std::begin(rhs), std::end(rhs));
return retval;
}
PartialFactors toPartialFactors(const Factors & f) {
PartialFactors retval;
retval.first.resize(f.size());
for (size_t i = 0; i < f.size(); ++i)
retval.first[i] = i;
retval.second = f;
return retval;
}
size_t toIndex(const Factors & space, const Factors & f) {
size_t result = 0; size_t multiplier = 1;
for (size_t i = 0; i < f.size(); ++i) {
result += multiplier * f[i];
multiplier *= space[i];
}
return result;
}
void toFactors(const Factors & space, size_t id, Factors * out) {
assert(out);
auto & f = *out;
for (size_t i = 0; i < space.size(); ++i) {
f[i] = id % space[i];
id /= space[i];
}
}
size_t toIndex(const Factors & space, const PartialFactors & f) {
size_t result = 0; size_t multiplier = 1;
for (size_t i = 0, j = 0; i < space.size(); ++i) {
if (i == f.first[j]) {
result += multiplier * f.second[j++];
if (j == f.first.size()) break;
}
multiplier *= space[i];
}
return result;
}
Factors toFactors(const Factors & space, size_t id) {
Factors f(space.size());
toFactors(space, id, &f);
return f;
}