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A2Z Sheet

311. Diameter of Binary Tree

Easy
Step 13: Binary Trees [Traversals, Medium and Hard Problems]›Medium Problems

Diameter of Binary Tree

EasyFunction: diameterOfBinaryTree()
ASCI Mission Breakdown • Simple as Hell
"Master Diameter of Binary Tree: Take `nums` (number[]) and `target` (number), execute an optimal medium problems strategy, and return number with clean edge-case handling."
Real-World Metaphor:

Think of Diameter of Binary Tree as an everyday real-world challenge: you receive input data, inspect its elements in sequence without making unnecessary duplicate passes, and transform the collection to reach the exact target without wasting computer memory.

Interactive Visual WalkthroughBINARY-TREE
Step 1 / 3
StatusInitialized
ModeScanning
Evaluating

1. Initialize State for Diameter of Binary Tree

Load inputs and initialize algorithmic registers.

How to Think About This (Mental Model)

  1. Unpack the problem parameters (`nums` (number[]) and `target` (number)) and clarify what is given vs what must be returned.
  2. Identify the optimal data structure or pattern (e.g. pointers, hash map, or stack) to avoid redundant recalculations.
  3. Walk through state transitions, handle edge cases (empty collections, single items, negative numbers), and return the verified result.

Given a sorted array of integers `nums` and an integer `target`, find the index or answer corresponding to **Diameter of Binary Tree**. Your solution must achieve logarithmic runtime complexity `O(log N)`.

Examples

Example 1
Input: nums = [1,3,5,6], target = 5
Output: 2
Explanation: 5 is found at index 2.
Example 2
Input: nums = [1,3,5,6], target = 2
Output: -1
Explanation: 2 is not present in the array.

Constraints

  • 1 <= nums.length <= 10^5
  • -10^9 <= nums[i], target <= 10^9
Topic Tags:
Binary Trees [Traversals, Medium and Hard Problems]Medium ProblemsdiameterOfBinaryTree
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