Using Big Oh notation, indicate the time requirement of each of the following tasks in the worst case. Describe any assumptions that you make. $(6$ points$)$

a$.$ After arriving at a party, you shake hands with each person there.

b$.$ Each person in a room shakes hands with everyone else in the room.

c$.$ You climb a flight of stairs.

e$.$ After entering an elevator, you press a button to choose a floor.

f$.$ You ride the elevator from the ground floor up to the nth floor.

g$.$ You read a book twice.

What is the Big Oh of the following computation? $(3$ points$)$

int sum $=0$;

for $\frac{\text{i}\text{n}\text{t}\text{c}\text{o}\text{u}\text{n}\text{t}\text{e}\text{r}}{\frac{?}{?}}=n$; counter $>0$; counter $=$ counter $-2$

sum $=$ sum $+$ counter;

Suppose that your implementation of a particular algorithm appears in Java as follows: $(4$ points$)$The algorithm involves an array of n items. The previous code shows the only repetition in the algorithm, but it does not show the computations that occur within the loops. These computations, however, are independent of n $.$ What is the order of the algorithm?