Tree Traversal Postorder Left Right Root in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the postorder traversal function recursively on the left child.

DSA Go

func postorder(node *Node) {
    if node == nil {
        return
    }
    postorder(node.[1])
    // Continue traversal
}

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ALeft

BRight

CParent

DRoot

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function on the right child first.

Calling the function on the node itself again.

Using incorrect field names.

In postorder traversal, we first visit the left child, so we call the function on node.Left.

2fill in blank

medium

Complete the code to call the postorder traversal function recursively on the right child.

DSA Go

func postorder(node *Node) {
    if node == nil {
        return
    }
    postorder(node.Left)
    postorder(node.[1])
    // Continue traversal
}

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ARight

BRoot

CLeft

DParent

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function on the left child again.

Calling the function on the node itself instead of a child.

Using incorrect field names.

After visiting the left child, postorder traversal visits the right child, so we call the function on node.Right.

3fill in blank

hard

Fix the error in the code to print the node's value after visiting its children.

DSA Go

func postorder(node *Node) {
    if node == nil {
        return
    }
    postorder(node.Left)
    postorder(node.Right)
    fmt.Println(node.[1])
}

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ALeft

BRight

CValue

DParent

Attempts:

3 left

💡 Hint

Common Mistakes

Printing the left or right child instead of the node's value.

Printing the parent pointer which may not exist.

Forgetting to print anything.

In postorder traversal, after visiting left and right children, we print the node's Value.

4fill in blank

hard

Fill both blanks to complete the postorder traversal function that returns a slice of node values.

DSA Go

func postorderValues(node *Node) []int {
    if node == nil {
        return []int{}
    }
    left := postorderValues(node.[1])
    right := postorderValues(node.[2])
    return append(append(left, right...), node.Value)
}

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ALeft

BRight

CParent

DRoot

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right children.

Using non-existent fields like Parent or Root.

Appending values in wrong order.

We recursively get values from the left child, then the right child, then add the current node's value.

5fill in blank

hard

Fill all three blanks to build a map of node values to their depths during postorder traversal.

DSA Go

func postorderDepthMap(node *Node, depth int, m map[int]int) {
    if node == nil {
        return
    }
    postorderDepthMap(node.[1], depth+1, m)
    postorderDepthMap(node.[2], depth+1, m)
    m[[3]] = depth
}

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ALeft

BRight

Cnode.Value

Ddepth

Attempts:

3 left

💡 Hint

Common Mistakes

Using depth as map key instead of node value.

Swapping left and right children.

Not increasing depth during recursion.

We recurse on left and right children increasing depth, then store the node's value with its depth in the map.