Question 35 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #1448. Count Good Nodes in Binary Tree

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:

test sample 1

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.

Example 2:

test sample 2

Input: root = [3,3,null,4,2]
Output: 3
Explanation: Node 2 -> (3, 3, 2) is not good, because "3" is higher than it.

Example 3:

Input: root = [1]
Output: 1
Explanation: Root is considered as good.



  • 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].
Video Solution
C++ Solution
					class Solution {
    void countGood(TreeNode* root, int &count, int currMax)

        countGood(root->left, count, currMax);
        countGood(root->right, count, currMax);
    int goodNodes(TreeNode* root) {
        int count=0;
        return count;

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