添加 problem 107

Algorithms/107. Binary Tree Level Order Traversal II/107. Binary Tree Level Order Traversal II.go

@@ -0,0 +1,18 @@
+package leetcode
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func levelOrderBottom(root *TreeNode) [][]int {
+	tmp := levelOrder(root)
+	res := [][]int{}
+	for i := len(tmp) - 1; i >= 0; i-- {
+		res = append(res, tmp[i])
+	}
+	return res
+}

Algorithms/107. Binary Tree Level Order Traversal II/107. Binary Tree Level Order Traversal II_test.go

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+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question107 struct {
+	para107
+	ans107
+}
+
+// para 是参数
+// one 代表第一个参数
+type para107 struct {
+	one []int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans107 struct {
+	one [][]int
+}
+
+func Test_Problem107(t *testing.T) {
+
+	qs := []question107{
+
+		question107{
+			para107{[]int{}},
+			ans107{[][]int{}},
+		},
+
+		question107{
+			para107{[]int{1}},
+			ans107{[][]int{[]int{1}}},
+		},
+
+		question107{
+			para107{[]int{3, 9, 20, NULL, NULL, 15, 7}},
+			ans107{[][]int{[]int{15, 7}, []int{9, 20}, []int{3}}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 107------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans107, q.para107
+		fmt.Printf("【input】:%v      ", p)
+		root := Ints2TreeNode(p.one)
+		fmt.Printf("【output】:%v      \n", levelOrderBottom(root))
+	}
+	fmt.Printf("\n\n\n")
+}

Algorithms/107. Binary Tree Level Order Traversal II/README.md

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+# [107. Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii/)
+
+## 题目
+
+Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).
+
+For example:
+Given binary tree [3,9,20,null,null,15,7],
+
+```c
+    3
+   / \
+  9  20
+    /  \
+   15   7
+```
+
+return its bottom-up level order traversal as:
+
+
+```c
+[
+  [15,7],
+  [9,20],
+  [3]
+]
+```
+ 
+
+## 题目大意
+
+按层序从下到上遍历一颗树。用一个队列即可实现。
+
+
+