package q110

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

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func isBalancedInternal(node *TreeNode, lvl int) (bool, int) {
	if node == nil {
		return true, lvl
	}

	lBal, lDpth := isBalancedInternal(node.Left, lvl+1)
	rBal, rDpth := isBalancedInternal(node.Right, lvl+1)
	dpth := max(lDpth, rDpth)

	if !lBal || !rBal || abs(lDpth-rDpth) > 1 {
		return false, dpth
	}
	return true, dpth
}

func isBalanced(root *TreeNode) bool {
	ret, _ := isBalancedInternal(root, 0)
	return ret
}

var _ = isBalanced