BST Property and Why It Matters in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a node's left child value is greater than or equal to the node's value.

DSA Typescript

if (node.left && node.left.value [1] node.value) {
  return false;
}

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

A>=

B<

C>

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' or '<=' instead of '>=' causes incorrect BST validation.

Confusing left and right child comparisons.

The BST property requires left child values to be less than the node's value.

2fill in blank

medium

Complete the code to check if a node's right child value is less than or equal to the node's value.

DSA Typescript

if (node.right && node.right.value [1] node.value) {
  return false;
}

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

A>

B<

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' or '>=' instead of '<=' causes wrong BST validation.

Mixing up left and right child checks.

The BST property requires right child values to be greater than the node's value.

3fill in blank

hard

Fix the error in the BST validation condition for the left subtree.

DSA Typescript

return isBST(node.left, [1], node.value) && isBST(node.right, node.value, max);

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

Anull

Bnode.value

Cmin

Dmax

Attempts:

3 left

💡 Hint

Common Mistakes

Passing node.value as min causes incorrect range checks.

Using max instead of min for left subtree boundaries.

The left subtree must have values between min and the current node's value.

4fill in blank

hard

Fill both blanks to complete the BST validation recursive calls with correct boundaries.

DSA Typescript

return isBST(node.left, [1], node.value) && isBST(node.right, node.value, [2]);

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

Amin

Bmax

Cnode.value

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping min and max in recursive calls.

Using node.value for both boundaries.

Left subtree values must be between min and node.value; right subtree values between node.value and max.

5fill in blank

hard

Fill all three blanks to complete the BST property check in the recursive function.

DSA Typescript

if (!node) return true;
if (node.value [1] min || node.value [2] max) return false;
return isBST(node.left, min, [3]) && isBST(node.right, node.value, max);

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

A<=

B>=

Cnode.value

Dmin

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' or '>' instead of '<=' or '>=' causes boundary errors.

Passing min instead of node.value as new max boundary.

Check if node.value is not less or equal to min, and not greater or equal to max. Then recurse with updated boundaries.