# 543. Diameter of Binary Tree
## Problem Statement
Given the `root` of a binary tree, return *the length of the **diameter** of the tree*.
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`.
The **length** of a path between two nodes is represented by the number of edges between them.
**Example 1:**
Input: root = [1,2,3,4,5]
Output: 3
Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
**Example 2:**
Input: root = [1,2]
Output: 1
**Constraints:**
* The number of nodes in the tree is in the range `[1, 104]`.
* `-100 <= Node.val <= 100`
## Intuition
```
Find the max of l+r at each step
Basically longest node to longest
```
### Links
### Video Links
### Approach 1:
```
```
{% code title="C++" lineNumbers="true" %}
```cpp
class Solution {
public:
int maxi=0;
int find_ans(TreeNode* root){
if(root==nullptr)
return 0;
int l = find_ans(root->left);
int r = find_ans(root->right);
maxi = max(maxi, l+r);
return 1 + max(l,r);
}
int diameterOfBinaryTree(TreeNode* root) {
find_ans(root);
return maxi;
}
};
```
{% endcode %}
### Approach 2:
```
```
{% code title="C++" lineNumbers="true" %}
```cpp
```
{% endcode %}
### Approach 3:
```
```
{% code title="C++" lineNumbers="true" %}
```cpp
```
{% endcode %}
### Approach 4:
```
```
{% code title="C++" lineNumbers="true" %}
```cpp
```
{% endcode %}
### Similar Problems
###
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