Boundary Traversal of Binary Tree in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

DSA Go

func newNode(val int) *Node {
    return &Node{
        data: [1],
        left: nil,
        right: nil,
    }
}

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Avalue

Bval

Cnode

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name not defined in the function like 'value' or 'node'.

The function parameter is named 'val', so we assign 'val' to the node's data field.

2fill in blank

medium

Complete the code to check if a node is a leaf node (no children).

DSA Go

func isLeaf(node *Node) bool {
    return node != nil && node.left == nil && node.[1] == nil
}

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Aparent

Bchild

Cright

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Checking a non-existent field like 'child' or 'parent'.

A leaf node has both left and right children as nil, so we check node.right == nil.

3fill in blank

hard

Fix the error in the code to traverse the left boundary of the tree (excluding leaves).

DSA Go

func addLeftBoundary(root *Node, res *[]int) {
    curr := root.left
    for curr != nil {
        if !isLeaf(curr) {
            *res = append(*res, curr.data)
        }
        if curr.left != nil {
            curr = curr.[1]
        } else {
            curr = curr.right
        }
    }
}

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Aleft

Bright

Cparent

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using curr.right instead of curr.left when left child exists.

To traverse the left boundary, we move down the left child if it exists.

4fill in blank

hard

Fill both blanks to add the right boundary nodes in reverse order (excluding leaves).

DSA Go

func addRightBoundary(root *Node, res *[]int) {
    curr := root.[1]
    var tmp []int
    for curr != nil {
        if !isLeaf(curr) {
            tmp = append(tmp, curr.data)
        }
        if curr.[2] != nil {
            curr = curr.[2]
        } else {
            curr = curr.left
        }
    }
    for i := len(tmp) - 1; i >= 0; i-- {
        *res = append(*res, tmp[i])
    }
}

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Aright

Bleft

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from root.left or moving down left children for right boundary.

Start from root.right and move down right children to collect right boundary nodes.

5fill in blank

hard

Fill all three blanks to collect all leaf nodes in left-to-right order.

DSA Go

func addLeaves(root *Node, res *[]int) {
    if root == nil {
        return
    }
    if isLeaf(root) {
        *res = append(*res, root.[1])
        return
    }
    addLeaves(root.[2], res)
    addLeaves(root.[3], res)
}

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Adata

Bleft

Cright

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Appending wrong field like 'value' or traversing right child before left.

Append the data of leaf nodes and recursively traverse left then right children.