How should I practice Symmetric Binary Tree?

Start by reading the full statement, solve the visible examples, then compare the pattern against related DocuSign phone screen problems in FastPrep.

Is Symmetric Binary Tree associated with DocuSign?

FastPrep tags this as a DocuSign phone screen coding practice problem when the problem catalog has that company and stage context.

Symmetric Binary Tree

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Problem statement

Given the root of a binary tree, return true when the tree is symmetric around its center and false otherwise.

Two subtrees mirror each other when their root values are equal, the left subtree of one mirrors the right subtree of the other, and the right subtree of one mirrors the left subtree of the other.

Function

isSymmetric(root: TreeNode) → boolean

Examples

Example 1

root = [1,2,2,3,4,4,3]return = true

The left and right subtrees have equal values in mirrored positions.

Example 2

root = [1,2,2,null,3,null,3]return = false

The two nodes with value 3 occupy matching sides rather than mirrored sides.

Example 3

root = []return = true

An empty tree has no mismatched mirrored pair.

Constraints

The tree contains at most 10^5 nodes.
Each node value fits in a signed 32-bit integer.
The empty tree is symmetric.