https://leetcode.com/problems/diameter-of-binary-tree/description

### Understanding the Problem:

Before diving into the solution, let’s understand the problem statement. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root node.

### Approach and Code Explanation:

To solve the diameter of a binary tree problem, we’ll use a recursive approach. We’ll define a helper function `recurse`

that calculates the height of the binary tree rooted at a given node and updates the maximum diameter encountered so far.

Here’s the breakdown of the Java solution:

```
class Solution {
public int maxLength = -1;
public int diameterOfBinaryTree(TreeNode root) {
recurse(root);
return maxLength;
}
public int recurse(TreeNode node) {
if (node == null) {
return 0;
}
int left = recurse(node.left);
int right = recurse(node.right);
maxLength = Math.max(maxLength, left + right);
return 1 + Math.max(left, right);
}
}
```

- We define a class
`Solution`

that contains the solution logic. - We declare a class variable
`maxLength`

to store the maximum diameter encountered. - The
`diameterOfBinaryTree`

method is the entry point of our solution. It invokes the`recurse`

method to compute the diameter of the binary tree rooted at the given`root`

node. - The
`recurse`

method calculates the height of the binary tree rooted at a given node. It returns the height of the subtree rooted at the current node. Additionally, it updates the`maxLength`

variable with the maximum diameter encountered so far.