Build Heap from Array Heapify in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the parent index of a node in a heap.

DSA Go

parent := (index - 1) [1] 2

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A*

B/

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division

Adding instead of subtracting 1

The parent index in a heap is calculated by subtracting 1 from the current index and dividing by 2.

2fill in blank

medium

Complete the code to swap two elements in the heap array.

DSA Go

heap[i], heap[j] = heap[[1]], heap[i]

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Aj

Bi

Clen(heap)-1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping with the wrong index

Assigning the same element twice

To swap elements at positions i and j, assign heap[i] to heap[j] and heap[j] to heap[i].

3fill in blank

hard

Fix the error in the condition to check if left child exists in heapify.

DSA Go

if left < [1] {

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Alen(heap) + 1

Blen(heap) - 1

Clen(heap)

Dcap(heap)

Attempts:

3 left

💡 Hint

Common Mistakes

Using length-1 instead of length

Using capacity instead of length

The left child index must be less than the length of the heap array to exist.

4fill in blank

hard

Fill both blanks to complete the heapify function's recursive call and comparison.

DSA Go

if right < len(heap) && heap[right] [1] heap[largest] {
    largest = [2]
}

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A>

B<

Cright

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>'

Assigning left instead of right

We check if the right child is greater than the current largest, then update largest to right.

5fill in blank

hard

Complete the code to complete the buildHeap function that heapifies from bottom up.

DSA Go

for i := len(heap)/2 - 1; i >= 0; i[1] {
    heapify(heap, i, len(heap))
}

func heapify(heap []int, i, n int) {
    largest := i
    left := 2*i + 1
    right := 2*i + 2
    if left < n && heap[left] > heap[largest] {
        largest = left
    }
    if right < n && heap[right] > heap[largest] {
        largest = right
    }
    if largest != i {
        heap[i], heap[largest] = heap[largest], heap[i]
        heapify(heap, largest, n)
    }
}

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A--

B+

C)

D]

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of -- in loop

Missing closing parenthesis

Incorrect argument for heapify

The loop decreases i by 1 each time (--). The heapify function needs the size n, so len(heap) + 0 is just len(heap). The closing parenthesis is needed to close the function call.