Data structures part 2

Question 1

What is a set

Answer 1

Sorted in ascending order
unique values only
can add or remove but not modify
based on sorting not indexing

Question 2

Create a set and print its elements

Answer 2

include <set></set>

set<string> cars;</string>

set<string> cars = {"Volvo", "BMW", "Ford", "Mazda"};</string>

// Print set elements
for (string car : cars) {
cout &laquo_space;car &laquo_space;“\n”;
}

Question 3

How are sets sorted

Answer 3

alphabetically or numerically
1234
abcd

Question 4

Sort a set in descending order

Answer 4

// Sort elements in a set in descending order
set<int, greater<int>> numbers = {1, 7, 3, 2, 5, 9};
// Print the elements
for (int num : numbers) {
cout << num << "\n";
}</int>

Question 5

Add an element to a set

Answer 5

car.insert(“element”)

Question 6

Remove a specific element

Answer 6

cars.erase(“Volvo”)

Question 7

Remove all items from a set

Answer 7

cars.clear()

Question 8

Check if a set is empty

Answer 8

cars.empty()

Question 9

loop through a set

Answer 9

set<string> cars = {"Volvo", "BMW", "Ford", "Mazda"};</string>

for (string car : cars) {
cout &laquo_space;car &laquo_space;“\n”;
}

Question 10

What is a map

Answer 10

Stores key:value pairs, so basically a dictionary
stored in ascending order

You will need to define the key and value data type

Question 11

Create a map

Answer 11

include <map>

map<string, int> people = { {“John”, 32}, {“Adele”, 45}, {“Bo”, 29} };

Question 12

Access the value for a key named ‘john’ in a map called ‘people’

Answer 12

cout &laquo_space;people[“john”]

or cout &laquo_space;people.at(“John”)

at is preferred

Question 13

Add elements to a map

Answer 13

people[“Jenny”] = 22;

or

people.insert({“Jenny”, 32});

Question 14

Can you have two elements with equal keys?

Answer 14

No, values can be equal though

Question 15

Remove a specific element from a map

Answer 15

people.erase(“John”)

Question 16

Remove all elements from a map

Answer 16

people.clear()

Question 17

Show how many elements a map has

Answer 17

people.size()

Question 18

Check if the map is empty

Answer 18

empty();

Question 19

Show if the key “John” exists

Answer 19

people.count(“John”)

Question 20

Loop through a map

Now loop through these in reverse order

Answer 20

map<string, int> people = { {“John”, 32}, {“Adele”, 45}, {“Bo”, 29} };

for (auto person : people) {
cout &laquo_space;person.first &laquo_space;” is: “ &laquo_space;person.second &laquo_space;“\n”;
}

auto - auto detects data type
.first - for keys
.second - for values

map<string, int, greater<string>> people = { {"John", 32}, {"Adele", 45}, {"Bo", 29} };</string>

for (auto person : people) {
cout &laquo_space;person.first &laquo_space;” is: “ &laquo_space;person.second &laquo_space;“\n”;
}