Leetcode-543. Diameter of Binary Tree

Description:

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.

Examples:

          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.

C++ Solution:

/** * 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 diameterOfBinaryTree(TreeNode* root) {        if(!root)   return 0;        int rootL = deepLen(root->left) + deepLen(root->right);        int leftL = diameterOfBinaryTree(root->left);        int rightL= diameterOfBinaryTree(root->right);        return max(rootL, max(leftL,rightL));    }    int deepLen(TreeNode* root)    {        if(!root) return 0;        return max(deepLen(root->left), deepLen(root->right))+1;    }};