Check whether a binary tree is a mirror of itself
Coding problemEasyAsked in: Adobe, Amazon, Apple, Google, Meta, Microsoft
Given the root of a binary tree, return true if the tree is symmetric around its centre, and false otherwise. A tree is symmetric when its left subtree is a mirror image of its right subtree: same values, with left and right swapped at every level.
Trees are written in level order, with null for a missing child. An empty tree and a single node are symmetric.
Examples
Example 1
Input: root = [1,2,2,3,4,4,3]
Output: true
Example 2
Input: root = [1,2,2,null,3,null,3]
Output: false
Both 3s are right children; a mirror needs one left and one right.
Example 3
Input: root = []
Output: true
Constraints
- The tree has between 0 and 100,001 nodes
- Each value is a 32-bit integer
Run checks the 3 examples. Submit also runs the hidden tests: edge cases, large inputs and a time limit.
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