What is the Big-o analysis and time complexity for this code

Question

I was wondering if someone could please explain what the time complexity is for the codes below I Have been trying but I couldn't find the answer

first code:

for (k = 0; k < n / 2; ++k)
{
}
for (j = 0; j < n * n; ++j)
{
}```


second code:

``` k = n;
while (k > 1)
{

k /= 2;
}```