Check if Two Trees are Symmetric in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if both nodes are nil, which means symmetric at this point.

DSA Go

if [1] == nil && q == nil {
    return true
}

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Ap

Bq

Croot

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Checking only one node for nil instead of both.

Using wrong variable names.

We check if the first node 'p' is nil and the second node 'q' is nil to confirm symmetry at this point.

2fill in blank

medium

Complete the code to check if either node is nil, which means trees are not symmetric.

DSA Go

if p == nil || [1] == nil {
    return false
}

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Aq

Broot

Cnode

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Checking wrong variable for nil.

Using && instead of || in the condition.

We check if either 'p' or 'q' is nil. If one is nil and the other is not, trees are not symmetric.

3fill in blank

hard

Fix the error in the comparison of node values to check if they are equal.

DSA Go

if p.Val != [1].Val {
    return false
}

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Aroot

Bleft

Cnode

Dq

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with wrong variable.

Using assignment '=' instead of comparison '!='.

We compare the value of node 'p' with node 'q' to check if they are equal for symmetry.

4fill in blank

hard

Fill both blanks to recursively check the left subtree of p with the right subtree of q, and the right subtree of p with the left subtree of q.

DSA Go

return isSymmetricHelper(p.[1], q.[2]) && isSymmetricHelper(p.[3], q.[4])

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ALeft

BRight

Cleft

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase field names which are incorrect in Go.

Swapping the subtree checks incorrectly.

We check left subtree of p with right subtree of q and right subtree of p with left subtree of q to confirm symmetry.

5fill in blank

hard

Fill both blanks to complete the main function that calls the helper with the root node twice.

DSA Go

func isSymmetric(root *TreeNode) bool {
    if root == nil {
        return true
    }
    return isSymmetricHelper(root[1], root[2])
}

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A.Left

B.Right

D.Root

Attempts:

3 left

💡 Hint

Common Mistakes

Passing root.Left or root.Right instead of root.

Adding extra fields that cause errors.

The helper function is called with the root node twice without accessing subfields here.