package q1372

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

func zigZagLen(node *TreeNode, isLeft bool, curLen int) int {
	if node == nil {
		return 0
	}
	var l, r int
	if isLeft {
		l = zigZagLen(node.Left, true, 1)
		r = zigZagLen(node.Right, false, curLen+1)
	} else {
		l = zigZagLen(node.Left, true, curLen+1)
		r = zigZagLen(node.Right, false, 1)
	}
	return max(curLen, l, r)
}

func longestZigZag(root *TreeNode) int {
	if root == nil {
		return 0
	}
	return max(
		zigZagLen(root.Left, true, 1),
		zigZagLen(root.Right, false, 1),
	)
}

var _ = longestZigZag