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 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.
題意：二叉樹的最大直徑风秤，
即一個節(jié)點的最大直徑 = 它左樹的高度 + 它右樹的高度
思路：
可以將二叉樹的直徑轉(zhuǎn)換為：二叉樹的每個節(jié)點的左右子樹的高度和的最大值宵蕉。
/**
* 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 res=0;
int diameterOfBinaryTree(TreeNode* root) {
dfs(root);
return res;
}
int dfs(TreeNode* root)
{
if(root==NULL)
return 0;
int left=dfs(root->left);
int right=dfs(root->right);
res= max(left+right,res);
return max(left,right)+1;
}
};
