Diameter of Binary Tree.cpp

/*

Diameter of Binary Tree
Solution
Given a binary tree, you need to compute 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.

Example:
Given a binary tree
          1
         / \
        2   3
       / \     
      4   5    
Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].

Note: The length of path between two nodes is represented by the number of edges between them.

*/

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