Diameter of Binary Tree

Diameter of Binary Tree

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 longestpath 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.

解析：递归求解每个节点地 深度和通过每个节点地最长半径，找到所有节点地最长半径

代码：

/** * 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) {        int dist=0;        int depth=maxdepth(root,dist);        return dist;    }        int maxdepth(TreeNode* root,int &dist)    {        if (root==NULL)        {            dist=0;            return 0;        }        else        {            int leftdist=0,rightdist=0;            int leftdepth=maxdepth(root->left,leftdist);            int rightdepth=maxdepth(root->right,rightdist);            dist=max(leftdist,rightdist);            dist=max(dist,leftdepth+rightdepth);            return max(leftdepth,rightdepth)+1;        }    }};