#1448

Count Good Nodes in Binary Tree

medium· Treesruns: 0

Given the root of a binary tree, a node X is named good if no node on the path from the root to X has a value greater than X's value. Return the number of good nodes in the binary tree.

wpm 0acc 100%time 0:000 / 442

class Solution:
    def goodNodes(self, root: TreeNode) -> int:
        def dfs(node: TreeNode | None, max_so_far: int) -> int:
            if not node:
                return 0
            count = 1 if node.val >= max_so_far else 0
            max_so_far = max(max_so_far, node.val)
            count += dfs(node.left, max_so_far)
            count += dfs(node.right, max_so_far)
            return count

        return dfs(root, root.val)

click the box to focus · tab inserts 4 spaces · backspace to correct · esc to pause

desktop only

codedrill is a typing game and needs a real keyboard. open this on a laptop or desktop to practice.

you can still browse problems and sections from your phone.