RosettaCodeData/Task/Kolakoski-sequence/C++/kolakoski-sequence.cpp

58 lines
1.4 KiB
C++

#include <iostream>
#include <vector>
using Sequence = std::vector<int>;
std::ostream& operator<<(std::ostream& os, const Sequence& v) {
os << "[ ";
for (const auto& e : v) {
std::cout << e << ", ";
}
os << "]";
return os;
}
int next_in_cycle(const Sequence& s, size_t i) {
return s[i % s.size()];
}
Sequence gen_kolakoski(const Sequence& s, int n) {
Sequence seq;
for (size_t i = 0; seq.size() < n; ++i) {
const int next = next_in_cycle(s, i);
Sequence nv(i >= seq.size() ? next : seq[i], next);
seq.insert(std::end(seq), std::begin(nv), std::end(nv));
}
return { std::begin(seq), std::begin(seq) + n };
}
bool is_possible_kolakoski(const Sequence& s) {
Sequence r;
for (size_t i = 0; i < s.size();) {
int count = 1;
for (size_t j = i + 1; j < s.size(); ++j) {
if (s[j] != s[i]) break;
++count;
}
r.push_back(count);
i += count;
}
for (size_t i = 0; i < r.size(); ++i) if (r[i] != s[i]) return false;
return true;
}
int main() {
std::vector<Sequence> seqs = {
{ 1, 2 },
{ 2, 1 },
{ 1, 3, 1, 2 },
{ 1, 3, 2, 1 }
};
for (const auto& s : seqs) {
auto kol = gen_kolakoski(s, s.size() > 2 ? 30 : 20);
std::cout << "Starting with: " << s << ": " << std::endl << "Kolakoski sequence: "
<< kol << std::endl << "Possibly kolakoski? " << is_possible_kolakoski(kol) << std::endl;
}
return 0;
}