add new solutions

solutions/6/q637/solution.go

@@ -0,0 +1,43 @@
+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