Package g1401_1500.s1448_count_good_nodes_in_binary_tree

Class Solution

  • public class Solution
extends Object
    1448 - Count Good Nodes in Binary Tree.

    Medium

    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: 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:

    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.

    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].

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • goodNodes

        public int goodNodes​(TreeNode root)