Practice/LinkedIn/Leetcode 101. Symmetric Tree

Leetcode 101. Symmetric Tree

CodingMust

Problem

Given the root of a binary tree, determine whether it exhibits mirror symmetry around its vertical center axis. A tree is considered symmetric if you can draw a vertical line through the root and the left side is a perfect reflection of the right side.

For the tree to be symmetric, every node on the left subtree must have a corresponding node at the mirrored position in the right subtree with the same value. Additionally, the structural arrangement must also be mirrored.

Requirements

1. Return true if the tree is symmetric, false otherwise
2. Handle empty trees (should return true)
3. Handle single-node trees (should return true)
4. Consider both node values and structural positions when checking symmetry

Constraints

• The number of nodes in the tree is in the range [0, 1000]
• -100 <= Node.val <= 100
• Follow-up: Can you solve this both recursively and iteratively?

Examples

Example 1:

` Input: root = [1, 2, 2, 3, 4, 4, 3] Tree structure: 1 /
2 2 / \ /
3 4 4 3

Output: true Explanation: The left subtree (2, 3, 4) mirrors the right subtree (2, 4, 3). Each corresponding position has matching values. `

Example 2:

` Input: root = [1, 2, 2, null, 3, null, 3] Tree structure: 1 /
2 2 \
3 3

Output: false Explanation: The right children don't mirror each other. The left subtree's node 2 has a right child, while the right subtree's node 2 also has a right child (should be left child for symmetry). `

Example 3:

Input: root = [1] Output: true Explanation: A tree with only one node is symmetric.