diff --git a/codes/python/chapter_array_and_linkedlist/array.py b/codes/python/chapter_array_and_linkedlist/array.py
index 7f34472c7..8933fb482 100644
--- a/codes/python/chapter_array_and_linkedlist/array.py
+++ b/codes/python/chapter_array_and_linkedlist/array.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: array.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_array_and_linkedlist/linked_list.py b/codes/python/chapter_array_and_linkedlist/linked_list.py
index d176d8dd2..dce110340 100644
--- a/codes/python/chapter_array_and_linkedlist/linked_list.py
+++ b/codes/python/chapter_array_and_linkedlist/linked_list.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: linked_list.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_array_and_linkedlist/list.py b/codes/python/chapter_array_and_linkedlist/list.py
index ac71b98b8..b0e2f2536 100644
--- a/codes/python/chapter_array_and_linkedlist/list.py
+++ b/codes/python/chapter_array_and_linkedlist/list.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: list.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_array_and_linkedlist/my_list.py b/codes/python/chapter_array_and_linkedlist/my_list.py
index 077fc0ce5..550e66955 100644
--- a/codes/python/chapter_array_and_linkedlist/my_list.py
+++ b/codes/python/chapter_array_and_linkedlist/my_list.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: my_list.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_computational_complexity/leetcode_two_sum.py b/codes/python/chapter_computational_complexity/leetcode_two_sum.py
index 182caec39..cb3bf3b02 100644
--- a/codes/python/chapter_computational_complexity/leetcode_two_sum.py
+++ b/codes/python/chapter_computational_complexity/leetcode_two_sum.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: leetcode_two_sum.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_computational_complexity/space_complexity.py b/codes/python/chapter_computational_complexity/space_complexity.py
index 69c1ac015..7efe8d948 100644
--- a/codes/python/chapter_computational_complexity/space_complexity.py
+++ b/codes/python/chapter_computational_complexity/space_complexity.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: space_complexity.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_computational_complexity/time_complexity.py b/codes/python/chapter_computational_complexity/time_complexity.py
index a3e698384..bfb5b3b11 100644
--- a/codes/python/chapter_computational_complexity/time_complexity.py
+++ b/codes/python/chapter_computational_complexity/time_complexity.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: time_complexity.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_computational_complexity/worst_best_time_complexity.py b/codes/python/chapter_computational_complexity/worst_best_time_complexity.py
index 7b052a3e0..b70dce4f0 100644
--- a/codes/python/chapter_computational_complexity/worst_best_time_complexity.py
+++ b/codes/python/chapter_computational_complexity/worst_best_time_complexity.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: worst_best_time_complexity.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_searching/binary_search.py b/codes/python/chapter_searching/binary_search.py
index 3d9ee0ffc..275ae28ec 100644
--- a/codes/python/chapter_searching/binary_search.py
+++ b/codes/python/chapter_searching/binary_search.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_search.py
 Created Time: 2022-11-26
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_searching/hashing_search.py b/codes/python/chapter_searching/hashing_search.py
index 68cffe64a..f49c703be 100644
--- a/codes/python/chapter_searching/hashing_search.py
+++ b/codes/python/chapter_searching/hashing_search.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: hashing_search.py
 Created Time: 2022-11-26
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_searching/linear_search.py b/codes/python/chapter_searching/linear_search.py
index 933095653..8ff9e0803 100644
--- a/codes/python/chapter_searching/linear_search.py
+++ b/codes/python/chapter_searching/linear_search.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: linear_search.py
 Created Time: 2022-11-26
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_sorting/bubble_sort.py b/codes/python/chapter_sorting/bubble_sort.py
index 54260dd96..610e3186c 100644
--- a/codes/python/chapter_sorting/bubble_sort.py
+++ b/codes/python/chapter_sorting/bubble_sort.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: bubble_sort.py
 Created Time: 2022-11-25
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_sorting/insertion_sort.py b/codes/python/chapter_sorting/insertion_sort.py
index db85515d1..bf8492cdd 100644
--- a/codes/python/chapter_sorting/insertion_sort.py
+++ b/codes/python/chapter_sorting/insertion_sort.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: insertion_sort.py
 Created Time: 2022-11-25
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_sorting/merge_sort.py b/codes/python/chapter_sorting/merge_sort.py
index 533fb9de7..f3fb538ae 100644
--- a/codes/python/chapter_sorting/merge_sort.py
+++ b/codes/python/chapter_sorting/merge_sort.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: merge_sort.py
 Created Time: 2022-11-25
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_sorting/quick_sort.py b/codes/python/chapter_sorting/quick_sort.py
index 5ba826bfa..f5ce8120c 100644
--- a/codes/python/chapter_sorting/quick_sort.py
+++ b/codes/python/chapter_sorting/quick_sort.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: quick_sort.py
 Created Time: 2022-11-25
 Author: timi (xisunyy@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_stack_and_queue/array_queue.py b/codes/python/chapter_stack_and_queue/array_queue.py
index 7408f2ba2..947c06091 100644
--- a/codes/python/chapter_stack_and_queue/array_queue.py
+++ b/codes/python/chapter_stack_and_queue/array_queue.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: array_queue.py
 Created Time: 2022-12-01
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import os.path as osp
 import sys
diff --git a/codes/python/chapter_stack_and_queue/array_stack.py b/codes/python/chapter_stack_and_queue/array_stack.py
index 889a372dc..18aee16b0 100644
--- a/codes/python/chapter_stack_and_queue/array_stack.py
+++ b/codes/python/chapter_stack_and_queue/array_stack.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: array_stack.py
 Created Time: 2022-11-29
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_stack_and_queue/deque.py b/codes/python/chapter_stack_and_queue/deque.py
index 7881a965e..30444c6b3 100644
--- a/codes/python/chapter_stack_and_queue/deque.py
+++ b/codes/python/chapter_stack_and_queue/deque.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: deque.py
 Created Time: 2022-11-29
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import os.path as osp
 import sys
diff --git a/codes/python/chapter_stack_and_queue/linkedlist_queue.py b/codes/python/chapter_stack_and_queue/linkedlist_queue.py
index 0d4a28d4d..2ab7196d3 100644
--- a/codes/python/chapter_stack_and_queue/linkedlist_queue.py
+++ b/codes/python/chapter_stack_and_queue/linkedlist_queue.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: linkedlist_queue.py
 Created Time: 2022-12-01
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import os.path as osp
 import sys
diff --git a/codes/python/chapter_stack_and_queue/linkedlist_stack.py b/codes/python/chapter_stack_and_queue/linkedlist_stack.py
index 5ee90353b..21f6ca6af 100644
--- a/codes/python/chapter_stack_and_queue/linkedlist_stack.py
+++ b/codes/python/chapter_stack_and_queue/linkedlist_stack.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: linkedlist_stack.py
 Created Time: 2022-11-29
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_stack_and_queue/queue.py b/codes/python/chapter_stack_and_queue/queue.py
index 740d9b1e1..ce220d7c1 100644
--- a/codes/python/chapter_stack_and_queue/queue.py
+++ b/codes/python/chapter_stack_and_queue/queue.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: queue.py
 Created Time: 2022-11-29
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import os.path as osp
 import sys
diff --git a/codes/python/chapter_stack_and_queue/stack.py b/codes/python/chapter_stack_and_queue/stack.py
index a8d2a7a50..5e95258fe 100644
--- a/codes/python/chapter_stack_and_queue/stack.py
+++ b/codes/python/chapter_stack_and_queue/stack.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: stack.py
 Created Time: 2022-11-29
 Author: Peng Chen (pengchzn@gmail.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_tree/binary_search_tree.py b/codes/python/chapter_tree/binary_search_tree.py
index f9dd9ec95..0f855f279 100644
--- a/codes/python/chapter_tree/binary_search_tree.py
+++ b/codes/python/chapter_tree/binary_search_tree.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_search_tree.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_tree/binary_tree.py b/codes/python/chapter_tree/binary_tree.py
index 78afa868e..81828b5cf 100644
--- a/codes/python/chapter_tree/binary_tree.py
+++ b/codes/python/chapter_tree/binary_tree.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_tree.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_tree/binary_tree_bfs.py b/codes/python/chapter_tree/binary_tree_bfs.py
index 43f192206..9ae1b3594 100644
--- a/codes/python/chapter_tree/binary_tree_bfs.py
+++ b/codes/python/chapter_tree/binary_tree_bfs.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_tree_bfs.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/chapter_tree/binary_tree_dfs.py b/codes/python/chapter_tree/binary_tree_dfs.py
index f8415ef56..094bd4cb5 100644
--- a/codes/python/chapter_tree/binary_tree_dfs.py
+++ b/codes/python/chapter_tree/binary_tree_dfs.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_tree_dfs.py
 Created Time: 2022-11-25
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
diff --git a/codes/python/include/binary_tree.py b/codes/python/include/binary_tree.py
index 24acb47d4..de2569e42 100644
--- a/codes/python/include/binary_tree.py
+++ b/codes/python/include/binary_tree.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: binary_tree.py
 Created Time: 2021-12-11
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 import collections
 
diff --git a/codes/python/include/linked_list.py b/codes/python/include/linked_list.py
index f6773c6f2..e2eff9a2c 100644
--- a/codes/python/include/linked_list.py
+++ b/codes/python/include/linked_list.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: linked_list.py
 Created Time: 2021-12-11
 Author: Krahets (krahets@163.com)
-'''
+"""
 
 class ListNode:
     """Definition for a singly-linked list node
diff --git a/codes/python/include/print_util.py b/codes/python/include/print_util.py
index f84d548b4..9f211806c 100644
--- a/codes/python/include/print_util.py
+++ b/codes/python/include/print_util.py
@@ -1,8 +1,8 @@
-'''
+"""
 File: print_util.py
 Created Time: 2021-12-11
 Author: Krahets (krahets@163.com), msk397 (machangxinq@gmail.com)
-'''
+"""
 
 import copy
 import queue
diff --git a/docs/chapter_computational_complexity/time_complexity.md b/docs/chapter_computational_complexity/time_complexity.md
index a482c7ae1..0313c533b 100644
--- a/docs/chapter_computational_complexity/time_complexity.md
+++ b/docs/chapter_computational_complexity/time_complexity.md
@@ -325,7 +325,7 @@ $T(n)$ 是个一次函数，说明时间增长趋势是线性的，因此易得
     $$
     T(n) \leq c \cdot f(n)
     $$
-    则可认为 $f(n)$ 给出了 $T(n)$ 的一个渐近上界，记为 
+    则可认为 $f(n)$ 给出了 $T(n)$ 的一个渐近上界，记为
     $$
     T(n) = O(f(n))
     $$
diff --git a/docs/chapter_introduction/what_is_dsa.md b/docs/chapter_introduction/what_is_dsa.md
index 12ba333b1..67b3c37e1 100644
--- a/docs/chapter_introduction/what_is_dsa.md
+++ b/docs/chapter_introduction/what_is_dsa.md
@@ -31,12 +31,23 @@ comments: true
 - 算法是发挥数据结构优势的舞台。数据结构仅存储数据信息，结合算法才可解决特定问题。
 - 算法有对应最优的数据结构。给定算法，一般可基于不同的数据结构实现，而最终执行效率往往相差很大。
 
-如果将数据结构与算法比作「LEGO 乐高」，数据结构就是乐高「积木」，而算法就是把积木拼成目标形态的一系列「操作步骤」。
-
 ![relationship_between_data_structure_and_algorithm](what_is_dsa.assets/relationship_between_data_structure_and_algorithm.png)
 
 <p align="center"> Fig. 数据结构与算法的关系 </p>
 
+如果将「LEGO 乐高」类比到「数据结构与算法」，那么可以得到下表所示的对应关系。
+
+<div class="center-table" markdown>
+
+| 数据结构与算法 | LEGO 乐高                                |
+| -------------- | ---------------------------------------- |
+| 输入数据       | 未拼装的积木                             |
+| 数据结构       | 积木组织形式，包括形状、大小、连接方式等 |
+| 算法           | 把积木拼成目标形态的一系列操作步骤       |
+| 输出数据       | 积木模型                                 |
+
+</div>
+
 !!! tip "约定俗成的简称"
 
     在实际讨论中，我们通常会将「数据结构与算法」直接简称为「算法」。例如，我们熟称的 LeetCode 算法题目，实际上同时考察了数据结构和算法两部分知识。
diff --git a/docs/chapter_tree/binary_tree.assets/array_representation_complete_binary_tree.png b/docs/chapter_tree/binary_tree.assets/array_representation_complete_binary_tree.png
new file mode 100644
index 000000000..f369d5d58
Binary files /dev/null and b/docs/chapter_tree/binary_tree.assets/array_representation_complete_binary_tree.png differ
diff --git a/docs/chapter_tree/binary_tree.assets/array_representation_mapping.png b/docs/chapter_tree/binary_tree.assets/array_representation_mapping.png
new file mode 100644
index 000000000..5c51843bc
Binary files /dev/null and b/docs/chapter_tree/binary_tree.assets/array_representation_mapping.png differ
diff --git a/docs/chapter_tree/binary_tree.assets/array_representation_with_empty.png b/docs/chapter_tree/binary_tree.assets/array_representation_with_empty.png
new file mode 100644
index 000000000..7d1be8dd1
Binary files /dev/null and b/docs/chapter_tree/binary_tree.assets/array_representation_with_empty.png differ
diff --git a/docs/chapter_tree/binary_tree.assets/array_representation_without_empty.png b/docs/chapter_tree/binary_tree.assets/array_representation_without_empty.png
new file mode 100644
index 000000000..d0f5d9bc1
Binary files /dev/null and b/docs/chapter_tree/binary_tree.assets/array_representation_without_empty.png differ
diff --git a/docs/chapter_tree/binary_tree.md b/docs/chapter_tree/binary_tree.md
index f5e3b7b9d..ed4582904 100644
--- a/docs/chapter_tree/binary_tree.md
+++ b/docs/chapter_tree/binary_tree.md
@@ -377,3 +377,82 @@ comments: true
 | 树的结点总数为 $n$ 时的高度 | $\log_2 (n+1) - 1$ | $n - 1$     |
 
 </div>
+
+## 二叉树表示方式 *
+
+我们一般使用二叉树的「链表表示」，即存储单位为结点 `TreeNode` ，结点之间通过指针（引用）相连接。本文前述示例代码展示了二叉树在链表表示下的各项基本操作。
+
+那能否可以用「数组表示」二叉树呢？答案是肯定的。先来分析一个简单案例，给定一个「完美二叉树」，将结点按照层序遍历的顺序编号（从 0 开始），那么可以推导得出父结点索引与子结点索引之间的「映射公式」：**设结点的索引为 $i$ ，则该结点的左子结点索引为 $2i + 1$ 、右子结点索引为 $2i + 2$** 。
+
+**本质上，映射公式的作用就是链表中的指针**。对于层序遍历序列中的任意结点，我们都可以使用映射公式来访问子结点。因此，可以直接使用层序遍历序列（即数组）来表示完美二叉树。
+
+![array_representation_mapping](binary_tree.assets/array_representation_mapping.png)
+
+然而，完美二叉树只是个例，二叉树中间层往往存在许多空结点（即 `null` ），而层序遍历序列并不包含这些空结点，并且我们无法单凭序列来猜测空结点的数量和分布位置，**即理论上存在许多种二叉树都符合该层序遍历序列**。显然，这种情况无法使用数组来存储二叉树。
+
+![array_representation_without_empty](binary_tree.assets/array_representation_without_empty.png)
+
+为了解决此问题，考虑按照完美二叉树的形式来表示所有二叉树，**即在序列中使用特殊符号来显式地表示“空位”**。如下图所示，这样处理后，序列（数组）就可以唯一表示二叉树了。
+
+=== "Java"
+
+    ```java title=""
+    /* 二叉树的数组表示 */
+    // 使用 int 的包装类 Integer ，就可以使用 null 来标记空位
+    Integer[] tree = { 1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15 };
+    ```
+
+=== "C++"
+
+    ```cpp title=""
+    /* 二叉树的数组表示 */
+    // 为了符合数据类型为 int ，使用 int 最大值标记空位
+    // 该方法的使用前提是没有结点的值 = INT_MAX
+    vector<int> tree = { 1, 2, 3, 4, INT_MAX, 6, 7, 8, 9, INT_MAX, INT_MAX, 12, INT_MAX, INT_MAX, 15 };
+    ```
+
+=== "Python"
+
+    ```python title=""
+    “”“ 二叉树的数组表示 ”“”
+    # 直接使用 None 来表示空位
+    tree = [1, 2, 3, 4, None, 6, 7, 8, 9, None, None, 12, None, None, 15]
+    ```
+
+=== "Go"
+
+    ```go title=""
+    
+    ```
+
+=== "JavaScript"
+
+    ```js title=""
+    
+    ```
+
+=== "TypeScript"
+
+    ```typescript title=""
+    
+    ```
+
+=== "C"
+
+    ```c title=""
+    
+    ```
+
+=== "C#"
+
+    ```csharp title=""
+    
+    ```
+
+![array_representation_with_empty](binary_tree.assets/array_representation_with_empty.png)
+
+回顾「完全二叉树」的满足条件，其只有最底层有空结点，并且最底层的结点尽量靠左，因而所有空结点都一定出现在层序遍历序列的末尾。**因为我们先验地确定了空位的位置，所以在使用数组表示完全二叉树时，可以省略存储“空位”**。“便于使用数组表示”也是完全二叉树受欢迎的原因之一。
+
+![array_representation_complete_binary_tree](binary_tree.assets/array_representation_complete_binary_tree.png)
+
+数组表示有两个优点： 一是不需要存储指针，节省空间；二是可以随机访问结点。然而，当二叉树中的“空位”很多时，数组中只包含很少结点的数据，空间利用率很低。