#pragma once

#include <algorithm>
#include <cstddef>
#include <iostream>
#include <utility>
#include <vector>

void sort_pair(std::pair<int, int>* pairs, size_t len);
void sort_pairs(std::pair<int, int>* pairs, size_t len);

template <typename T>
std::pair<int, int>* create_pairs(const T& array, size_t len)
{
	std::pair<int, int>* pairs = new std::pair<int, int>[len];

	for (size_t i = 0; i < len; i++)
	{
		pairs[i].second = array[i * 2];
		if (array.size() > i * 2 + 1)
			pairs[i].first = array[i * 2 + 1];
	}
	if (len % 2)
		pairs[len - 1].first = pairs[len - 1].second;
	return pairs;
}

template <typename T>
size_t binary_search(const T& array, size_t start, size_t end, int value) {
	if (array[end] < value)
		return end;

	while (true)
	{
		int mid = start + ((end - start) / 2);
		int min_value = array[mid];
		
		if (min_value == value || end - start <= 1)
		{
			if (min_value < value)
				return mid + 1;
			return mid;
		}
		else if (min_value < value)
			start = mid;
		else if (min_value > value)
			end = mid;
	}
}

template <typename T>
void insert_sort(const std::pair<int, int>* pairs, size_t len, T& array)
{
	for (size_t i = 1; i < len; i++)
	{
		array.push_back(pairs[i].first);
		if (pairs[i].first == pairs[i].second)
			continue;
		size_t index = binary_search(array, 0, array.size() - 1, pairs[i].second);
		array.insert(array.begin() + index, pairs[i].second);
	}
}

template <typename T>
void PmergeMe(T& array)
{
	if (array.size() < 2)
		return;
	std::size_t len = array.size() / 2 + array.size() % 2;
	std::pair<int, int>* pairs = create_pairs(array, len);
	sort_pair(pairs, len);
	sort_pairs(pairs, len);
	array.clear();
	array.push_back(pairs[0].second);
	if (pairs[0].second != pairs[0].first)
		array.push_back(pairs[0].first);
	insert_sort(pairs, len, array);
	delete[] pairs;
}