test_tasks/Test/Header.h

#pragma once
#include <iostream>
#include <map>
#include <utility>

template<typename T1, typename T2 >
inline void Print(const std::map<T1,T2>& cont)
{
	for (const auto& [f,s] : cont)
	{
		std::cout << f << ":" <<s<<" ";
	}
	std::cout << std::endl;
}

//Ðåàëèçîâàòü ôóíêöèþ, ïðîðåæèâàþùóþ èñõîäíóþ ïîñëåäîâàòåëüíîñòü ñëåäóþùèì îáðàçîì :
// êàæäîé ïîäïîñëåäîâàòåëüíîñòè èäåíòè÷íûõ îòñ÷åòîâ îñòàâèòü 
// òîëüêî ïåðâûé è ïîñëåäíèé îòñ÷åòû, à òàê æå êàæäûé n - íûé îòñ÷åò(n > 2).
//Âûâåñòè íà ýêðàí ïîñëåäîâàòåëüíîñòü äî è ïîñëå ïðèìåíåíèÿ ôóíêöèè ïðîðåæèâàíèÿ.

bool thin_out(std::map<int, int>& cont, int n)
{
	bool fl = false;

	std::pair<const int,int>* first = &(*cont.begin());
	auto last = first;
	auto pattern = (*std::begin(cont)).second;;
	int count = 0;

	for (auto& x : cont)
	{
		if (pattern == x.second)
		{
			count++;
			last = &x;
		}
		else if (count >2)
		{
			int key = (first->first);

			for (int i = 2; i < count; i++)
			{
				++key;
				
				if(i == n) continue;
				
				cont.erase(key);
				
			}
			pattern = x.second;
			first = &x;
			count = 1;

			fl = true;
		}
		else
		{
			pattern = x.second;
			first = &x;
			count = 1;
		}
	}

	return fl;
}