Serialize and Deserialize Binary Tree 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

func NewNode(val int) *TreeNode {
    return &TreeNode{Val: [1]
}

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Anil

BTreeNode{}

C0

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed value like 0 instead of the input parameter.

Returning nil instead of a new node.

The function should return a pointer to a TreeNode with the value set to the input val.

2fill in blank

medium

Complete the code to append a string to the builder during serialization.

DSA Go

func serializeHelper(root *TreeNode, sb *strings.Builder) {
    if root == nil {
        sb.WriteString("#,")
        return
    }
    sb.WriteString(strconv.Itoa([1]))
    sb.WriteString(",")
    serializeHelper(root.Left, sb)
    serializeHelper(root.Right, sb)
}

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Aroot.Left

B0

Croot.Val

Droot.Right

Attempts:

3 left

💡 Hint

Common Mistakes

Appending left or right child pointers instead of the node value.

Appending a fixed number like 0.

We need to convert the current node's value to string and append it. So root.Val is correct.

3fill in blank

hard

Fix the error in the deserialization code to correctly parse the next token.

DSA Go

func deserializeHelper(tokens *[]string, index *int) *TreeNode {
    if *index >= len(*tokens) {
        return nil
    }
    val := (*tokens)[*index]
    [1]
    if val == "#" {
        return nil
    }
    num, _ := strconv.Atoi(val)
    node := &TreeNode{Val: num}
    node.Left = deserializeHelper(tokens, index)
    node.Right = deserializeHelper(tokens, index)
    return node
}

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Aindex++

B*index += 1

C(*index)++

D*index++

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid syntax like *index++.

Incrementing the pointer itself instead of the value.

In Go, to increment the value pointed by a pointer, use *index += 1. The syntax *index++ is invalid.

4fill in blank

hard

Fill both blanks to complete the code that splits the serialized string and starts deserialization.

DSA Go

func deserialize(data string) *TreeNode {
    tokens := strings.Split(data, [1])
    index := 0
    return deserializeHelper(&tokens, [2])
}

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A","

B"#"

C&index

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Splitting by wrong delimiter like "#".

Passing index instead of &index.

The serialized string uses commas to separate tokens, so split by ",". The helper needs a pointer to index, so pass &index.

5fill in blank

hard

Fill all three blanks to complete the Serialize function that returns the serialized string.

DSA Go

func Serialize(root *TreeNode) string {
    var sb [1]
    serializeHelper(root, &sb)
    result := sb.[2]()
    return result[:len(result)-[3]]
}

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Astrings.Builder

BString

CStringBuilder

DStringBuffer

EString()

FToString()

GLen()

HLength()

I1

J2

K3

L4

Attempts:

3 left

💡 Hint

Common Mistakes

Using Java-like classes such as StringBuilder or StringBuffer.

Calling non-existent methods like ToString().

Removing wrong number of characters from the end.

Use strings.Builder to build the string. Call String() to get the string. Remove the last comma, so subtract 1.