Heap 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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Aa

Bb

Ctemp

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning 'a' to 'temp' again instead of 'b'.

Using '0' instead of 'b'.

The swap function exchanges the values of a and b by using a temporary variable. After storing a in temp, a should be assigned the value of b.

2fill in blank

medium

Complete the code to heapify a subtree rooted with index i.

DSA C++

void heapify(int arr[], int n, int i) {
    int largest = i;
    int left = 2 * i + 1;
    int right = 2 * i + 2;

    if (left < n && arr[left] [1] arr[largest])
        largest = left;

    if (right < n && arr[right] > arr[largest])
        largest = right;

    if (largest != i) {
        swap(arr[i], arr[largest]);
        heapify(arr, n, largest);
    }
}

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A<

B==

C>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' causing min-heap behavior.

Using '==' which does not help in comparison.

To maintain max-heap property, we check if the left child is greater than the current largest element.

3fill in blank

hard

Fix the error in the loop that builds the heap.

DSA C++

for (int i = n / 2 - 1; i >= [1]; i--) {
    heapify(arr, n, i);
}

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A0

B-1

Cn

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'n' or '1' as the stopping condition causes out-of-bound errors.

Using '-1' skips the root node.

Heap building starts from the last non-leaf node down to the root at index 0.

4fill in blank

hard

Fill both blanks to complete the heap sort extraction loop.

DSA C++

for (int i = n - 1; i > [1]; i--) {
    swap(arr[0], arr[i]);
    heapify(arr, i, [2]);
}

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A0

Bi

C1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'i' or 'n' in place of 0 causes incorrect heapify calls.

Stopping loop at wrong index skips sorting.

The loop runs until i > 0, and after swapping, heapify is called on the root index 0 with reduced heap size i.

5fill in blank

hard

Fill all three blanks to complete the heap sort function.

DSA C++

void heapSort(int arr[], int n) {
    for (int i = n / 2 - 1; i >= [1]; i--) {
        heapify(arr, n, i);
    }

    for (int i = n - 1; i > [2]; i--) {
        swap(arr[[3]], arr[i]);
        heapify(arr, i, 0);
    }
}

Drag options to blanks, or click blank then click option'

A0

B1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 or n instead of 0 for root index.

Incorrect loop stopping conditions.

The first loop builds the heap starting from index 0. The second loop extracts elements until i > 0. The swap uses index 0 as the root.