Question

To swap two elements of a python list, I need:

Select one:

a. a new element at the beginning of the list

b. a new element at the end of the list

Question text

To swap the content of two nodes from a doubly-linked-list, I need:

Select one:

a. a reference to previous only.

b. a reference to previous and a reference to next.

c. a temporary Doubly-Linked-List node.

d. a temporary variable to contain an object.

Question text

To be efficient, I can swap two variables containing integers with:

Select one:

a. no additional variables and two instructions.

b. no additional variables and three instructions.

c. one additional variable and two instructions.

d. one additional variable and three instructions.

c. a new list

d. a temporary variable

To swap two variables containing two different objects, I need:

Select one:

a. no additional variable

b. 2 additional variables

c. 1 additional variable

d. a pointer

Answer 1

1) a. a new element at the beginning of the list

2) d. a temporary variable to contain an object.

Explanation: In DLL, we can get the previous and next nodes using pointers. However, in order to swap two nodes, we would need to store the reference of one of the nodes in a temporary variable.

3) b. no additional variables and three instructions.

We can do something like:

x = x + y;

y = x - y;

x = x - y;

4) c. 1 additional variable

1 additional variable is required to store the reference of one of the objects.