8393번, 10818번, 2438번

8393번

#include<iostream>
#include<string>
using namespace std;

int main()
{
	int sum = 0;
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		sum = sum + i;
	}
	cout << sum;

}

 

10818번

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;

int main()
{
	int n = 0;
	cin >> n;
	vector<int> arr(n);
	for (int i = 0; i < n; i++)
	{
		cin >> arr[i];
	}
	sort(arr.begin(), arr.end());
	cout << arr[0] << ' ' << arr[n-1];
}

 

2438번

#include<iostream>
using namespace std;

int main()
{
	int n = 0;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j <= i; j++)
		{
			cout << '*';
		}
		cout << '\n';
	}
}