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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to traverse the left subtree first in postorder traversal.

DSA Javascript

function postorder(node) {
  if (node === null) return;
  postorder(node.[1]);
  // Continue traversal
}

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

Aparent

Bright

Croot

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'right' instead of 'left' for the first recursive call.

Trying to access a non-existent 'parent' property.

In postorder traversal, we visit the left subtree first, so we call postorder(node.left).

2fill in blank

medium

Complete the code to traverse the right subtree second in postorder traversal.

DSA Javascript

function postorder(node) {
  if (node === null) return;
  postorder(node.left);
  postorder(node.[1]);
  // Continue traversal
}

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

Aright

Bparent

Cchild

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'root' or 'parent' instead of 'right'.

Skipping the right subtree traversal.

In postorder traversal, after the left subtree, we visit the right subtree by calling postorder(node.right).

3fill in blank

hard

Fix the error in the code to visit the root node last in postorder traversal.

DSA Javascript

function postorder(node) {
  if (node === null) return;
  postorder(node.left);
  postorder(node.right);
  console.log(node.[1]);
}

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

Aright

Bleft

Cvalue

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

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

Printing before traversing subtrees.

We print the value of the node after visiting left and right subtrees in postorder traversal.

4fill in blank

hard

Fill both blanks to complete the recursive postorder traversal function.

DSA Javascript

function postorder(node) {
  if (node === null) return;
  postorder(node.[1]);
  postorder(node.[2]);
  console.log(node.value);
}

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

Aleft

Bright

Cparent

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right.

Using non-existent properties like 'parent' or 'child'.

Postorder traversal visits the left subtree, then the right subtree, and finally the root node.

5fill in blank

hard

Fill all three blanks to create a postorder traversal that collects values in an array.

DSA Javascript

function postorder(node, result) {
  if (node === null) return;
  postorder(node.[1], result);
  postorder(node.[2], result);
  result.[3](node.value);
}

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

Aleft

Bright

Cpush

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pop' instead of 'push' to add values.

Mixing up left and right children.

We recursively visit left and right subtrees, then add the node's value to the result array using push.