DSBA Introduction to Programming // Workshops 11, 12, 13, 14

Spring semester 2021/22

Dealing with maps, sets and their variations.

Task 4.

Recreate the original map (how many times an element has appeared in the vector) and the set as unordered_map and unordered_set.

Print them and compare the output of ordered and unordered containers.

4.1

Output paramenters of unordered_map when adding objects.

1. Check which bucked the new element will use with mapVariable.bucket(element)
2. Check the size of this bucket with mapVariable.bucket_size(bucketIndex)
3. Add the new element
4. Check the size again
5. Print bucket_count
6. Print load_factor.

Additional tasks

Task 5. Custom comparator

Explanation

Sort a vector of strings by length of the strings using a custom comparator.

Custom comparators are functions that take two arguments of the same type and return true if the first argument is less than the second one. They are similar to the key parameter in Python sorting functions.

Example:

bool compareAbs(int x, int y)
{
    return std::abs(x) < std::abs(y);
}

int main()
{
    VecInt exampleVector = generateVector(15, -5, 5);
    std::sort(exampleVector.begin(), exampleVector.end(), compareAbs);
    printVec(exampleVector);
    return 0;
}

This vector will be printed in the increasing order of the absolute value of it's elements.

Task

Create a vector of strings, for example:

std::vector<std::string> vecString = {"first string", "qwe", "z", "a word", "more words"};

Print this vector in the increasing order of the length of the string. Example output:

z
qwe
a word
more words
first string