Search for a Value in Linked List in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the linked list is empty.

DSA Go

if head == [1] {
    fmt.Println("List is empty")
}

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

Aempty

B0

Cnil

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or 'null' instead of nil.

Checking for an empty string instead of nil.

In Go, a linked list node pointer is nil when it points to nothing, meaning the list is empty.

2fill in blank

medium

Complete the code to move to the next node in the linked list.

DSA Go

current = current.[1]

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

Aprev

Blink

Cchild

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev which is for doubly linked lists.

Using incorrect field names like child or link.

Each node in a singly linked list has a next pointer to the next node.

3fill in blank

hard

Fix the error in the condition to check if the current node's value equals the target.

DSA Go

if current.[1] == target {
    fmt.Println("Value found")
}

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

Adata

Bval

Cvalue

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Using val or value when the field is named data.

Using node which is not a field.

The node's data is stored in the data field, which holds the value.

4fill in blank

hard

Fill both blanks to complete the loop that searches the linked list for the target value.

DSA Go

for current != [1] {
    if current.[2] == target {
        fmt.Println("Found")
        break
    }
    current = current.next
}

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

Anil

Bhead

Cdata

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using head instead of nil in the loop condition.

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

The loop continues until current is nil (end of list). The node's value is in data.

5fill in blank

hard

Fill all three blanks to create a function that searches for a value in a linked list and returns true if found.

DSA Go

func search(head *Node, target int) bool {
    current := [1]
    for current != [2] {
        if current.[3] == target {
            return true
        }
        current = current.next
    }
    return false
}

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

Ahead

Bnil

Cdata

Dtarget

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from nil instead of head.

Comparing the wrong field with target.

Start from head, loop until nil, and compare data with target.

Practice

1. What is the main purpose of searching for a value in a linked list?

easy

A. To reverse the order of nodes in the list

B. To add a new node at the end of the list

C. To delete the first node of the list

D. To find if a specific value exists in the list

Solution

1. Step 1: Understand the search operation

   Searching means checking each node to see if it contains the target value.

2. Step 2: Identify the goal of searching

   The goal is to find whether the value exists anywhere in the linked list.

3. Final Answer:

   To find if a specific value exists in the list -> Option D

4. Quick Check:

   Search means find value presence = To find if a specific value exists in the list [OK]

Hint: Search means look for a value in nodes [OK]

Common Mistakes:

• Confusing search with insertion or deletion
• Thinking search changes the list structure
• Assuming search reverses the list

2. Which of the following Go code snippets correctly checks if a linked list node's value equals the target value val?

easy

A. if current.val = val { return true }

B. if current.value == val { return true }

C. if current.value := val { return true }

D. if current.value != val { return true }

Solution

1. Step 1: Identify correct equality check syntax in Go

   Use double equals (==) to compare values, not single equals (=) or :=.

2. Step 2: Check the field name and comparison logic

   Assuming node field is 'value', 'current.value == val' correctly compares values.

3. Final Answer:

   if current.value == val { return true } -> Option B

4. Quick Check:

   Use '==' for comparison in Go [OK]

Hint: Use '==' to compare values, not '=' or ':=' [OK]

Common Mistakes:

• Using '=' instead of '==' for comparison
• Using ':=' inside if condition incorrectly
• Checking inequality instead of equality

3. What will be the output of the following Go code that searches for value 5 in a linked list?

type Node struct {
    value int
    next  *Node
}

func search(head *Node, val int) bool {
    current := head
    for current != nil {
        if current.value == val {
            return true
        }
        current = current.next
    }
    return false
}

// List: 1 -> 3 -> 5 -> 7 -> nil
head := &Node{1, &Node{3, &Node{5, &Node{7, nil}}}}
fmt.Println(search(head, 5))

medium

A. true

B. false

C. Compilation error

D. Runtime panic

Solution

1. Step 1: Trace the search function through the list

   It checks nodes 1, 3, then 5. When it finds 5, it returns true immediately.

2. Step 2: Confirm no errors occur

   Code is correct and will print true because 5 exists in the list.

3. Final Answer:

   true -> Option A

4. Quick Check:

   Value 5 found in list = true [OK]

Hint: Stop search when value found, else false [OK]

Common Mistakes:

• Assuming search returns false if value is in list
• Thinking code causes panic due to nil pointer
• Confusing output with string instead of boolean

4. Identify the bug in this Go function that searches for a value in a linked list:

func search(head *Node, val int) bool {
    current := head
    for current.next != nil {
        if current.value == val {
            return true
        }
        current = current.next
    }
    return false
}

medium

A. Loop condition misses checking the last node

B. Comparison uses '=' instead of '=='

C. Function returns true even if value not found

D. Variable 'current' is not initialized

Solution

1. Step 1: Analyze the loop condition

   The loop runs while current.next != nil, so it stops before last node.

2. Step 2: Understand impact on search

   The last node's value is never checked, so search can miss the value if it's there.

3. Final Answer:

   Loop condition misses checking the last node -> Option A

4. Quick Check:

   Loop must check all nodes including last [OK]

Hint: Use 'current != nil' to check all nodes [OK]

Common Mistakes:

• Using current.next != nil instead of current != nil
• Forgetting to check last node's value
• Misreading loop condition as correct

5. Given a linked list where nodes may contain duplicate values, how would you modify the search function to return the count of occurrences of a target value val instead of just true/false?
Choose the correct approach.

hard

A. Return true immediately when first node.value == val is found

B. Use recursion to return true if any node.value == val

C. Traverse all nodes, increment count when node.value == val, return count

D. Stop traversal when node.value != val is found

Solution

1. Step 1: Understand requirement to count all occurrences

   We must check every node because duplicates can appear anywhere.

2. Step 2: Modify search to count matches

   Traverse all nodes, increase count each time node.value equals val, then return count.

3. Final Answer:

   Traverse all nodes, increment count when node.value == val, return count -> Option C

4. Quick Check:

   Count all matches by full traversal [OK]

Hint: Count matches by checking every node [OK]

Common Mistakes:

• Stopping search after first match
• Returning boolean instead of count
• Ignoring duplicates in list