# LeetCode - 0543. Diameter of Binary Tree
### 題目網址：https://leetcode.com/problems/diameter-of-binary-tree/
###### tags: `LeetCode` `Easy` `動態規劃（Dynamic Programming）` `圖論`

/*
    -LeetCode format-
    Problem: 543. Diameter of Binary Tree
    Difficulty: Easy
    
    by Inversionpeter
*/



/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
    
    int diameter = 0;
    
    int Depths(TreeNode *node) {
        if (!node)
            return 0;
        int left = Depths(node->left), right = Depths(node->right);
        diameter = max(diameter, left + right);
        return max(left, right) + 1;
    }
    
public:
    int diameterOfBinaryTree(TreeNode* root) {
        Depths(root);
        return diameter;
    }
};