Va rog mult am mare nevoie

1.
Se afiseaza:
2 20 4 18 6 16 8 14 10 12
2.
#include <iostream>
using namespace std;
int main()
{
int k;
cin >> k;
for (int i = 1; i <= 100; ++i)
{
if (i * i % 10 == k)
{
cout << i << " ";
}
}
return 0;
}
3.
#include <iostream>
using namespace std;
int main()
{
int n, a[101];
bool ok = true;
cin >> n;
for (int i = 1; i <= n; ++i)
{
cin >> a[i];
}
for (int i = 1; i <= n; ++i)
{
for (int j = i + 1; j <= n; ++j)
{
if (a[i] == a[j])
{
ok = false;
}
}
}
if (ok)
{
cout << "DA";
}
else
{
cout << "NU";
}
return 0;
}