#include <iterator>
#include <algorithm>
#include <iostream>

template<typename T>
class CircularBuffer {
    T* data;
    size_t capacity_;
    size_t size_;
    size_t head_ = 0;
    
public:
    explicit CircularBuffer(size_t capacity) 
        : data(new T[capacity]), capacity_(capacity), size_(0) {}
    
    ~CircularBuffer() { delete[] data; }
    
    // Iterator class
    class iterator {
        T* ptr;
        size_t capacity;
        size_t index;
        
    public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = T;
        using difference_type = std::ptrdiff_t;
        using pointer = T*;
        using reference = T&;
        
        iterator(T* ptr, size_t capacity, size_t index)
            : ptr(ptr), capacity(capacity), index(index) {}
        
        reference operator*() { return ptr[index % capacity]; }
        pointer operator->() { return &ptr[index % capacity]; }
        
        iterator& operator++() {
            ++index;
            return *this;
        }
        
        iterator operator++(int) {
            iterator tmp = *this;
            ++index;
            return tmp;
        }
        
        bool operator==(const iterator& other) const {
            return index == other.index;
        }
        
        bool operator!=(const iterator& other) const {
            return !(*this == other);
        }
    };
    
    void push(const T& item) {
        data[(head_ + size_) % capacity_] = item;
        if (size_ < capacity_) {
            ++size_;
        } else {
            ++head_;
            head_ %= capacity_;
        }
    }
    
    iterator begin() { return iterator(data, capacity_, head_); }
    iterator end() { return iterator(data, capacity_, head_ + size_); }
    
    size_t size() const { return size_; }
    bool empty() const { return size_ == 0; }
};

int main() {
    CircularBuffer<int> buffer(5);
    
    // Заполняем буфер
    for (int i = 1; i <= 7; ++i) {
        buffer.push(i);
    }
    
    // Range-based for работает!
    for (const auto& item : buffer) {
        std::cout << item << " ";
    }
    std::cout << std::endl;
    
    // STL алгоритмы работают!
    auto it = std::find(buffer.begin(), buffer.end(), 5);
    if (it != buffer.end()) {
        std::cout << "Found: " << *it << std::endl;
    }
}