leet-code/count-good-nodes-in-binary-tree/sol.go

/*
 * @lc app=leetcode id=1448 lang=golang
 *
 * [1448] Count Good Nodes in Binary Tree
 */
package main

// @lc code=start
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
import "math"

func goodNodes(root *TreeNode) int {
	return subGoodNodes(root, math.MinInt)
}

func subGoodNodes(root *TreeNode, previousMax int) int {
	if root == nil {
		return 0
	}
	sum := 0
	max := previousMax
	if root.Val >= previousMax {
		sum = 1
		max = root.Val
	}
	sum += subGoodNodes(root.Left, max)
	sum += subGoodNodes(root.Right, max)
	return sum
}

// @lc code=end

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}