diameterOfBinaryTree.cpp

// Source : https://leetcode.com/problems/add-and-search-word-data-structure-design/
// Author : Arshdeep Singh
// Date   : 2021-10-01
/**
 * 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 {
private:
    int diameter;
    int maxDepth(TreeNode* root) {
        if(root==NULL) return 0;
        int left = maxDepth(root->left);
        int right = maxDepth(root->right);
        diameter = max(diameter, left + right);
        return 1 + max(left, right);
    }
public:
    int diameterOfBinaryTree(TreeNode* root) {
        diameter = 0;
        maxDepth(root);
        return diameter;
    }
};