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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to visit the left subtree first in inorder traversal.

DSA Javascript

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

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' causes wrong traversal order.

Using 'root' or 'parent' properties which do not exist.

In inorder traversal, we first visit the left child of the current node.

2fill in blank

medium

Complete the code to print the current node's value in inorder traversal.

DSA Javascript

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

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

Avalue

Bleft

Cright

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

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

Trying to print 'parent' which is not defined.

We print the current node's value after visiting the left subtree.

3fill in blank

hard

Fix the error in the inorder traversal to visit the right subtree correctly.

DSA Javascript

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

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

Aroot

Bleft

Cright

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left' instead of 'right' causes wrong traversal.

Using 'root' or 'parent' which are invalid here.

After visiting the root, inorder traversal visits the right child.

4fill in blank

hard

Fill both blanks to create a function that returns an array of inorder traversal values.

DSA Javascript

function inorderArray(node) {
  if (node === null) return [];
  return [...inorderArray(node.[1]), node.[2], ...inorderArray(node.right)];
}

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

Aleft

Bvalue

Cright

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right causes wrong order.

Using 'parent' or 'root' which are invalid.

We collect values from left subtree, then current node's value, then right subtree.

5fill in blank

hard

Fill all three blanks to create a function that builds a map of node values to their inorder positions.

DSA Javascript

function inorderMap(node, map = new Map(), index = {count: 0}) {
  if (node === null) return map;
  inorderMap(node.[1], map, index);
  map.set(node.[2], index.[3]);
  index.count++;
  inorderMap(node.right, map, index);
  return map;
}

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

Aleft

Bvalue

Ccount

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'right' instead of 'left' in first blank.

Using 'parent' or 'root' which do not exist.

Using 'index' instead of 'count' for the counter.

We traverse left subtree, map node's value to current count, then increment count and traverse right subtree.