Why Sorting Matters and How It Unlocks Other Algorithms in DSA C++ - Test Your Knowledge

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort the array using std::sort.

DSA C++

#include <algorithm>
#include <vector>

int main() {
    std::vector<int> data = {5, 3, 8, 1, 2};
    std::sort(data.[1]);
    return 0;
}

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Adata.begin(), end()

Bbegin(), data.end()

Cbegin(), end()

Ddata.begin(), data.end()

Attempts:

3 left

💡 Hint

Common Mistakes

Using begin() and end() without specifying the container causes errors.

Using data.begin() but forgetting data.end() or vice versa.

std::sort requires iterators to the beginning and end of the container. data.begin() and data.end() provide these iterators for the vector.

2fill in blank

medium

Complete the code to print the sorted vector elements.

DSA C++

#include <iostream>
#include <vector>

int main() {
    std::vector<int> data = {1, 2, 3, 5, 8};
    for (int [1] : data) {
        std::cout << [1] << " ";
    }
    return 0;
}

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Anum

Bi

Cval

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in the loop header and inside the loop body.

Using reserved keywords or invalid identifiers.

The variable name in the range-based for loop can be any valid identifier. Here, 'num' is used consistently to represent each element.

3fill in blank

hard

Fix the error in the binary search code by completing the condition.

DSA C++

#include <vector>
#include <algorithm>

bool contains(const std::vector<int>& data, int target) {
    return std::binary_search(data.begin(), data.end(), [1]);
}

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Atarget.begin()

Bdata.begin()

Ctarget

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the whole container instead of the target value.

Passing iterators instead of the value.

std::binary_search needs the target value to search for, not the container or iterators.

4fill in blank

hard

Fill both blanks to create a map of word lengths for words longer than 3 characters.

DSA C++

std::map<std::string, int> wordLengths;
for (const auto& word : words) {
    if (word.[1] > 3) {
        wordLengths[word] = word.[2];
    }

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Alength

Bsize

Clength()

Dsize()

Attempts:

3 left

💡 Hint

Common Mistakes

Using length or size without parentheses.

Using incorrect member function names.

In C++, std::string has member functions length() and size() that return the length of the string. Both are valid, but here length() is used in the condition and size() to assign the length.

5fill in blank

hard

Fill all three blanks to create a filtered map of uppercase words and their lengths for words longer than 4.

DSA C++

#include <map>
#include <string>
#include <algorithm>

std::map<std::string, int> filteredWords;
for (const auto& word : words) {
    if (word.[1] > 4) {
        std::string upperWord = word;
        std::transform(upperWord.[2], upperWord.[3], upperWord.begin(), ::toupper);
        filteredWords[upperWord] = word.size();
    }

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Asize()

Bbegin()

Cend()

Dlength()

Attempts:

3 left

💡 Hint

Common Mistakes

Using length() instead of size() inconsistently.

Forgetting parentheses on member functions.

Using incorrect iterators for std::transform.

To filter words longer than 4, use size(). std::transform needs iterators to the start and end of the string, so begin() and end() are used.