Push Using Linked List Node in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new node with the given value.

DSA Go

newNode := &Node{data: [1], next: nil}

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

Avalue

Bhead

Cnext

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'head' instead of the value for the new node's data.

Setting data to nil which is invalid for int type.

We create a new node with data set to the given value.

2fill in blank

medium

Complete the code to link the new node to the current head of the list.

DSA Go

newNode.next = [1]

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

Avalue

BnewNode

Cnil

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Setting next to value instead of head.

Setting next to nil which breaks the list.

The new node's next pointer should point to the current head node.

3fill in blank

hard

Fix the error in updating the head pointer to the new node.

DSA Go

head = [1]

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

AnewNode

Bvalue

Chead.next

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning head to value or nil instead of newNode.

Assigning head to head.next which skips the new node.

After pushing, the head should point to the new node.

4fill in blank

hard

Fill both blanks to complete the push function that inserts a new node at the front.

DSA Go

func push(head **Node, value int) {
    newNode := &Node{data: [1], next: *head}
    *head = [2]
}

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

Avalue

Bhead

CnewNode

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Not using pointer dereference for head update.

Setting next to head instead of *head.

We create a new node with data as value and next pointing to current head, then update head to newNode.

5fill in blank

hard

Fill all three blanks to implement push that adds a new node at the front of the list.

DSA Go

func push(head **Node, value int) {
    newNode := &Node{data: [1], next: [2]
    [3] = newNode
}

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

A*head

Bvalue

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing head and *head when updating pointers.

Setting next to head instead of *head.

Assigning head instead of *head to newNode.

We set newNode data to value, next to *head (current head), then update *head to newNode.

Practice

1. What does the push operation do in a linked list when using a node?

easy

A. Deletes the entire linked list

B. Removes the last node from the list

C. Searches for a node with a specific value

D. Adds a new node at the beginning of the list

Solution

1. Step 1: Understand push operation in linked list

   The push operation adds a new node at the start (head) of the linked list.

2. Step 2: Effect of push on list structure

   The new node becomes the head, and its next pointer points to the previous head node.

3. Final Answer:

   Adds a new node at the beginning of the list -> Option D

4. Quick Check:

   Push = Add at head [OK]

Hint: Push always adds node at the start of the list [OK]

Common Mistakes:

• Thinking push adds at the end
• Confusing push with pop
• Assuming push deletes nodes

2. Which of the following is the correct syntax to create a new node and push it onto a linked list in Go?

easy

A. newNode := Node{data: 5}; head.next = newNode

B. newNode := &Node{data: 5, next: head}; head = newNode

C. newNode := &Node{5}; head = newNode.next

D. newNode := Node{data: 5, next: nil}; head = newNode.next

Solution

1. Step 1: Create a new node with data and next pointer

   In Go, use &Node{data: 5, next: head} to create a new node pointing to current head.

2. Step 2: Update head to new node

   Assign head = newNode to make newNode the new head of the list.

3. Final Answer:

   newNode := &Node{data: 5, next: head}; head = newNode -> Option B

4. Quick Check:

   New node points to head, then head updated [OK]

Hint: New node's next points to head, then head updated [OK]

Common Mistakes:

• Not using pointer (&) for new node
• Assigning head.next instead of head
• Setting next to nil instead of head

3. What will be the output linked list after executing this Go code?

type Node struct {
  data int
  next *Node
}

func main() {
  var head *Node = nil
  head = &Node{data: 1, next: head}
  head = &Node{data: 2, next: head}
  head = &Node{data: 3, next: head}
  printList(head)
}

func printList(node *Node) {
  for node != nil {
    fmt.Print(node.data, " -> ")
    node = node.next
  }
  fmt.Print("null")
}

medium

A. 3 -> 2 -> 1 -> null

B. 1 -> 2 -> 3 -> null

C. null

D. 1 -> null

Solution

1. Step 1: Trace node insertions

   First node with data 1 is pushed, head points to node 1.
   Then node 2 is pushed, head points to node 2, next points to node 1.
   Then node 3 is pushed, head points to node 3, next points to node 2.

2. Step 2: Print list from head

   Prints 3 -> 2 -> 1 -> null as nodes are added at front.

3. Final Answer:

   3 -> 2 -> 1 -> null -> Option A

4. Quick Check:

   Push adds at head, so list reversed [OK]

Hint: Push adds at head, so last pushed is first in list [OK]

Common Mistakes:

• Assuming push adds at tail
• Confusing order of nodes
• Ignoring nil termination

4. Identify the error in this Go code that tries to push a new node onto a linked list:

type Node struct {
  data int
  next *Node
}

func push(head *Node, data int) {
  newNode := &Node{data: data, next: head}
  head = newNode
}

func main() {
  var head *Node = nil
  push(head, 10)
  // printList(head) expected to show 10 -> null
}

medium

A. head is passed by value, so main's head is not updated

B. newNode is not created correctly with & operator

C. next pointer should be nil, not head

D. Function push should return void, not update head

Solution

1. Step 1: Analyze parameter passing

   head is passed by value to push, so changes inside push do not affect main's head.

2. Step 2: Effect on linked list head

   Assigning head = newNode inside push only changes local copy, main's head remains nil.

3. Final Answer:

   head is passed by value, so main's head is not updated -> Option A

4. Quick Check:

   Pointer must be passed by reference or returned [OK]

Hint: Pass head pointer by reference or return new head [OK]

Common Mistakes:

• Assuming pointer changes reflect outside function
• Not returning updated head
• Misunderstanding Go parameter passing

5. Given a linked list with nodes containing integers, how would you modify the push function to avoid memory leaks and ensure the list is correctly updated in Go?

hard

A. Use a slice instead of linked list for better memory management

B. Use a global variable for head instead of passing it

C. Make push return the new head node and assign it to head in main

D. Set newNode.next to nil before assigning head

Solution

1. Step 1: Understand pointer update requirement

   In Go, to update head outside push, function must return new head node.

2. Step 2: Assign returned head in main

   Call head = push(head, data) to update head correctly and avoid dangling pointers.

3. Final Answer:

   Make push return the new head node and assign it to head in main -> Option C

4. Quick Check:

   Return new head to update list safely [OK]

Hint: Return new head from push and assign it outside [OK]

Common Mistakes:

• Not returning updated head
• Using global variables unnecessarily
• Ignoring pointer semantics in Go