#+PROPERTY: STUDY_DECK_02 * TODO 1448. Count Good Nodes In Binary Tree :medium: :PROPERTIES: :NEETCODE: [[file:../../roadmap.org::*1448. Count Good Nodes In Binary Tree][1448. Count Good Nodes In Binary Tree]] :END: Given a binary tree ~root~, a node /X/ in the tree is named *good* if in the path from root to /X/ there are no nodes with a value /greater than/ X. Return the number of *good* nodes in the binary tree. *Example 1:* ** #+begin_src Input: root = [3,1,4,3,null,1,5] Output: 4 Explanation: Nodes in blue are good. Root Node (3) is always a good node. Node 4 -> (3,4) is the maximum value in the path starting from the root. Node 5 -> (3,4,5) is the maximum value in the path Node 3 -> (3,1,3) is the maximum value in the path. #+end_src *Example 2:* ** #+begin_src Input: root = [3,3,null,4,2] Output: 3 Explanation: Node 2 -> (3, 3, 2) is not good, because "3" is higher than it. #+end_src *Example 3:* #+begin_src Input: root = [1] Output: 1 Explanation: Root is considered as good. #+end_src *Constraints:* - The number of nodes in the binary tree is in the range ~[1, 10^5]~. - Each node's value is between ~[-10^4, 10^4]~. ** TODO Approach Write your approach here. ** TODO Python #+begin_src python # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def goodNodes(self, root: TreeNode) -> int: #+end_src ** TODO C++ #+begin_src cpp /** * 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 goodNodes(TreeNode* root) { } }; #+end_src