package q637

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

func averageOfLevels(root *TreeNode) []float64 {
	type qElem struct {
		level int
		node  *TreeNode
	}

	ret := []float64{}
	level := 0
	n := 0 // number of nodes
	var sum float64

	queue := []qElem{{level: 0, node: root}}
	for ; len(queue) > 0; queue = queue[1:] {
		curr := &queue[0]
		if curr.level == level {
			sum += float64(curr.node.Val)
			n++
		} else {
			ret = append(ret, sum/float64(n))
			sum = float64(curr.node.Val)
			n = 1
			level = curr.level
		}
		if curr.node.Left != nil {
			queue = append(queue, qElem{curr.level + 1, curr.node.Left})
		}
		if curr.node.Right != nil {
			queue = append(queue, qElem{curr.level + 1, curr.node.Right})
		}
	}
	ret = append(ret, sum/float64(n))
	return ret
}

var _ = averageOfLevels