1448. Count Good Nodes in Binary Tree

Medium

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128

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:**

Input:root = [3,1,4,3,null,1,5]Output:4Explanation:Nodes in blue aregood. 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:**

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

**Example 3:**

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

**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]`

.

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