#pragma once

#include <vector>
#include <math.h>

template<class It>
class IteratorRange {
public:
    IteratorRange(It b, It e) : begin_(b), end_(e), size_(std::distance(b, e)) {}

    It begin() const {
        return begin_;
    }

    It end() const {
        return end_;
    }

    size_t size() const {
        return size_;
    }
private:
    It begin_, end_;
    size_t size_;
};

template <typename It>
class Slicer {
public:
    Slicer(It begin, It end, int page_size) : size_(ceil(std::distance(begin, end) / static_cast<double>(page_size))) {
        It cur_iter = begin;
        while (cur_iter != end) {
            int elem = 0;
            begin = cur_iter;
            for (; (elem < page_size) && (cur_iter != end); elem++) {
                 ++cur_iter;
            }
            pages_.push_back(IteratorRange<It>(begin, cur_iter));
        }
    }
    auto begin() const {
        return pages_.begin();
    }

    auto end() const {
        return pages_.end();
    }

    size_t size() const {
        return size_;
    }
private:
    std::vector<IteratorRange<It>> pages_;
    size_t size_;
};

template<typename C>
auto Slice(C& c, size_t page_size) {
    return Slicer<typename C::iterator>(c.begin(), c.end(), page_size);
}

template<typename C>
auto Slice(const C& c, size_t page_size) {
    return Slicer<typename C::const_iterator>(c.begin(), c.end(), page_size);
}
template<>
auto Slice(const IteratorRange<std::vector<int>::iterator>& c, size_t page_size) {
    return Slicer<std::vector<int>::iterator>(c.begin(), c.end(), page_size);
}