Heap Insert Operation Bubble Up in DSA Rust - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a new element at the end of the heap vector.

DSA Rust

heap.push([1]);

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

Aheap

Bindex

Cvalue

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'index' or 'parent' instead of the actual value.

Trying to push the entire heap again.

We push the new value to the end of the heap vector before bubbling up.

2fill in blank

medium

Complete the code to find the parent index of the current node during bubble up.

DSA Rust

let parent = ([1] - 1) / 2;

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Avalue

Bindex

Cheap.len()

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'value' or 'heap.len()' instead of the current index.

Using addition instead of subtraction.

The parent index is calculated from the current index using (index - 1) / 2.

3fill in blank

hard

Fix the error in the condition to continue bubbling up while the current node is greater than its parent.

DSA Rust

while index > 0 && heap[[1]] > heap[parent] {

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Aindex

Bvalue

Cparent

Dheap.len()

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing parent with itself or wrong index.

Using 'value' or 'heap.len()' as index.

We compare the current node at 'index' with its parent to decide if we swap.

4fill in blank

hard

Fill both blanks to swap the current node with its parent and update the index.

DSA Rust

heap.swap([1], [2]);
index = [3];

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Aindex

Bparent

Cvalue

Dheap.len()

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping wrong indices or updating index incorrectly.

Using 'value' or 'heap.len()' in swap or index update.

Swap the current node at 'index' with its 'parent', then update 'index' to parent's position.

5fill in blank

hard

Fill all three blanks to complete the bubble up loop: calculate parent, check condition, and update parent.

DSA Rust

while index > 0 && heap[index] > heap[[1]] {
    heap.swap(index, [2]);
    index = [3];
}

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

Aparent

B(index - 1) / 2

Dindex - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parent calculation or updating index incorrectly.

Swapping with wrong indices.

Calculate parent as (index - 1) / 2, swap with parent, then update index to parent.

Practice

1. What is the main purpose of the bubble up operation during a heap insert?

easy

A. To swap the root with the last element

B. To restore the heap property by moving the inserted element up

C. To sort all elements in ascending order

D. To remove the smallest element from the heap

Solution

1. Step 1: Understand heap property

   A heap must maintain a specific order, usually parent nodes are greater (max-heap) or smaller (min-heap) than their children.

2. Step 2: Role of bubble up

   When a new element is inserted at the end, bubble up moves it up to restore the heap property if violated.

3. Final Answer:

   To restore the heap property by moving the inserted element up -> Option B

4. Quick Check:

   Bubble up fixes heap order after insert [OK]

Hint: Bubble up fixes heap order by moving new element up [OK]

Common Mistakes:

• Confusing bubble up with removing elements
• Thinking bubble up sorts the entire heap
• Believing bubble up swaps root with last element

2. Which Rust code snippet correctly swaps a child and its parent during bubble up in a max-heap?

easy

A. heap.swap(child_index, parent_index);

B. heap.insert(child_index, parent_index);

C. heap.remove(child_index);

D. heap.push(parent_index);

Solution

1. Step 1: Identify swap method usage

   To exchange two elements in a vector, Rust's Vec has a swap method taking two indices.

2. Step 2: Confirm correct parameters

   Swapping child and parent indices restores heap order during bubble up.

3. Final Answer:

   heap.swap(child_index, parent_index); -> Option A

4. Quick Check:

   swap() exchanges elements by index [OK]

Hint: Use Vec.swap(child, parent) to exchange elements [OK]

Common Mistakes:

• Using insert instead of swap
• Calling remove which deletes elements
• Using push which adds elements

3. Given the max-heap represented by the array [50, 30, 40, 10, 20], what will be the heap array after inserting 45 and performing bubble up?

medium

A. [50, 45, 40, 10, 20, 30]

B. [50, 30, 40, 10, 20, 45]

C. [50, 30, 45, 10, 20, 40]

D. [45, 30, 50, 10, 20, 40]

Solution

1. Step 1: Insert 45 at the end

   Array becomes [50, 30, 40, 10, 20, 45].

2. Step 2: Bubble up 45

   Parent of index 5 is index 2 (value 40). Since 45 > 40, swap them. New array: [50, 30, 45, 10, 20, 40].

3. Step 3: Check next parent

   Parent of index 2 is index 0 (value 50). 45 < 50, stop bubbling up.

4. Final Answer:

   [50, 30, 45, 10, 20, 40] -> Option C

5. Quick Check:

   Insert then bubble up swaps with parent if bigger [OK]

Hint: Insert at end, swap up while bigger than parent [OK]

Common Mistakes:

• Not swapping 45 with 40
• Swapping 45 with 30 incorrectly
• Stopping bubble up too early

4. In the following Rust code for bubble up, what is the bug?

fn bubble_up(heap: &mut Vec<i32>, mut index: usize) {
    while index > 0 {
        let parent = (index - 1) / 2;
        if heap[index] > heap[parent] {
            heap.swap(index, parent);
            index = parent;
        }
    }
}

medium

A. Loop condition should be index >= 0

B. Incorrect parent calculation formula

C. Using swap instead of insert

D. Missing update of index when no swap occurs, causing infinite loop

Solution

1. Step 1: Analyze loop behavior

   Loop runs while index > 0. Inside, swap and update index if heap[index] > heap[parent].

2. Step 2: Identify missing else case

   If heap[index] <= heap[parent], index is not updated, so loop never ends causing infinite loop.

3. Final Answer:

   Missing update of index when no swap occurs, causing infinite loop -> Option D

4. Quick Check:

   Loop must update index or break to avoid infinite loop [OK]

Hint: Always update index or break in bubble up loop [OK]

Common Mistakes:

• Ignoring infinite loop possibility
• Wrong parent index formula
• Confusing swap with insert
• Using invalid loop condition

5. You have a min-heap represented by [5, 10, 15, 20, 25]. You insert 12. After bubble up, what is the correct heap array?

hard

A. [5, 10, 12, 20, 25, 15]

B. [5, 10, 15, 20, 25, 12]

C. [5, 12, 10, 20, 25, 15]

D. [5, 10, 15, 12, 25, 20]

Solution

1. Step 1: Insert 12 at the end

   Array becomes [5, 10, 15, 20, 25, 12].

2. Step 2: Bubble up 12 in min-heap

   Parent of index 5 is index 2 (value 15). Since 12 < 15, swap them. New array: [5, 10, 12, 20, 25, 15].

3. Step 3: Check next parent

   Parent of index 2 is index 0 (value 5). 12 > 5, stop bubbling up.

4. Final Answer:

   [5, 10, 12, 20, 25, 15] -> Option A

5. Quick Check:

   Min-heap bubble up swaps if child smaller than parent [OK]

Hint: In min-heap, bubble up swaps smaller child with parent [OK]

Common Mistakes:

• Not swapping 12 with 15
• Stopping bubble up too early
• Confusing min-heap with max-heap rules