Add bt level order 2

Author: Gituser143

Easy/binary-tree-level-order-traversal-ii.md

@@ -0,0 +1,42 @@
+Code
+====
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func levelOrderBottom(root *TreeNode) [][]int {
+	levels := [][]int{}
+	if root == nil {
+		return levels
+	}
+
+	levelNodes := []*TreeNode{root}
+
+	for len(levelNodes) != 0 {
+		level := []int{}
+		nextLevel := []*TreeNode{}
+		for _, node := range levelNodes {
+			level = append(level, node.Val)
+			if node.Left != nil {
+				nextLevel = append(nextLevel, node.Left)
+			}
+
+			if node.Right != nil {
+				nextLevel = append(nextLevel, node.Right)
+			}
+		}
+		levelNodes = nextLevel
+		levels = append(levels, []int{})
+		copy(levels[1:], levels[:len(levels)-1])
+		levels[0] = level
+	}
+
+	return levels
+}
+```

README.md

@@ -91,6 +91,8 @@ Easy
 
 -	[check-if-two-string-arrays-are-equivalent](Easy/check-if-two-string-arrays-are-equivalent.md)
 
+-	[binary-tree-level-order-traversal-ii](Easy/binary-tree-level-order-traversal-ii.md)
+
 Medium
 ------