#include <iostream>
#include <list>
using namespace std;
 
int main() {
	list<int> list_1 = {1, 2, 4, 4, 6, 9};
	list<int> list_2 = {1, 0, 4, 4, 7, 8};
	list_1.unique(); // O(n)
	list_2.unique(); // O(n)
 
	list_1.splice(list_1.begin(), list_2, list_2.begin(), list_2.end()); // O(n)
 
	cout << "lists after join\n";
	for (int &i : list_1)
		cout << i << ' ';
 
	size_t before = list_1.size();
	list_1.sort(); // O(n * log2(n))
	list_1.unique(); // O(n)
	size_t after = list_1.size();
 
	cout << "\nlists after removing identical elements\n";
	for (int &i : list_1)
		cout << i << ' ';
 
	cout << "\nthere is " << before - after << " identical elements\n"; 
 
	return 0;
}

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