Quick Sort Algorithm in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to swap two elements in the array.

DSA C++

void swap(int& a, int& b) {
    int temp = a;
    a = [1];
    b = temp;
}

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A0

Ba

Ctemp

Db

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning 'a' to itself instead of 'b'.

Using 'temp' incorrectly.

We assign 'a' the value of 'b' to swap their values correctly.

2fill in blank

medium

Complete the code to choose the pivot element for partitioning.

DSA C++

int partition(int arr[], int low, int high) {
    int pivot = arr[[1]];
    int i = low - 1;
    for (int j = low; j < high; j++) {
        if (arr[j] < pivot) {
            i++;
            swap(arr[i], arr[j]);
        }
    }
    swap(arr[i + 1], arr[high]);
    return i + 1;
}

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Ahigh

Blow

Clow + 1

Dhigh - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing the wrong index for the pivot.

Using an index outside the array bounds.

The pivot is chosen as the last element at index 'high' for partitioning.

3fill in blank

hard

Fix the error in the recursive quickSort call to sort the left partition.

DSA C++

void quickSort(int arr[], int low, int high) {
    if (low < high) {
        int pi = partition(arr, low, high);
        quickSort(arr, low, [1]);
        quickSort(arr, pi + 1, high);
    }
}

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Api

Bpi - 1

Clow

Dhigh

Attempts:

3 left

💡 Hint

Common Mistakes

Including the pivot index in the left partition.

Using the wrong boundary for recursion.

The left partition ends at 'pi - 1' to exclude the pivot element.

4fill in blank

hard

Fill both blanks to complete the partition function's loop condition and swap call.

DSA C++

int partition(int arr[], int low, int high) {
    int pivot = arr[high];
    int i = low - 1;
    for (int j = low; j [1] high; j++) {
        if (arr[j] [2] pivot) {
            i++;
            swap(arr[i], arr[j]);
        }
    }
    swap(arr[i + 1], arr[high]);
    return i + 1;
}

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A<

B<=

C>

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' in the loop condition causing out-of-bound errors.

Using '>' instead of '<=' in the if condition.

The loop runs while j < high, and elements less than or equal to pivot are swapped.

5fill in blank

hard

Fill all three blanks to complete the quickSort function with correct recursive calls and base condition.

DSA C++

void quickSort(int arr[], int low, int high) {
    if (low [1] high) {
        int pi = partition(arr, low, high);
        quickSort(arr, low, [2]);
        quickSort(arr, [3], high);
    }
}

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A<

Bpi - 1

Cpi + 1

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators in the base condition.

Including the pivot index in recursive calls.

The base condition is 'low < high', and recursive calls sort left and right partitions excluding the pivot.