543. 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.

 

计算树中任意两个节点之间的路径，要求路径最长

 

C++（12ms）：

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     int diameterOfBinaryTree(TreeNode* root) {
13         int res = 0 ;
14         maxDepth(root,res) ;
15         return res ;
16         
17     }
18     
19     int maxDepth(TreeNode* root , int& res){
20         if (root == NULL) return 0 ;
21         int left = maxDepth(root->left,res) ;
22         int right = maxDepth(root->right,res) ;
23         res = max(res , left+right) ;
24         
25         return 1 + max(left,right) ;
26     }
27 };

 

posted @ 2017-12-15 10:10  __Meng  阅读(139)  评论(0)    收藏  举报