leetcode 543. Diameter of Binary Tree (DFS)
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.
思路:DFS
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int res;
int diameterOfBinaryTree(TreeNode* root) {
res=1;
dfs(root);
return res-1;
}
int dfs(TreeNode* r){
if(r==NULL)return 0;
int lef=dfs(r->left);
int rig=dfs(r->right);
res=max(res,lef+rig+1);
return max(lef,rig)+1;
}
};