diff --git a/README.md b/README.md
index 54b1380..82737d7 100644
--- a/README.md
+++ b/README.md
@@ -319,12 +319,34 @@ $$
 ## 8. [查找](ch7/README.md#查找)
 
 - [查找](ch7/README.md#1-基本概念)
-  - [顺序查找](ch7/README.md#2-顺序查找)
-  - [折半查找](ch7/README.md#3-折半查找)
-  - [分块查找](ch7/README.md#4-分块查找)
-  - [B 树](ch7/README.md#5-B-树)
-  - [B+树](ch7/README.md#6-B+-树)
-  - [散列表](ch7/README.md#7-散列表)
+  - [顺序查找](ch7/sequential-search/README.md#顺序查找)
+  - [折半查找](ch7/binary-search/README.md#折半查找)
+  - [分块查找](ch7/block-search/README.md#分块查找)
+  - [B 树](ch7/b-tree/README.md#B-树)
+  - [B+ 树](ch7/b-plus-tree/README.md#B+-树)
+  - [散列表](ch7/hash-table/README.md#散列表)
 - [串](ch4/README.md#串)
   - [基本概念](ch4/README.md#1-定义)
   - [模式匹配(KMP)](ch4/README.md#6-KMP-算法)
+
+## 9. [排序](ch8/README.md#排序)
+
+- 基本概念
+  - 排序定义
+  - 时空复杂度
+  - 稳定性
+- 内部排序
+  - 插入排序
+    - 直接插入排序
+    - 折半插入排序
+    - 希尔排序
+  - 交换排序
+    - 冒泡排序
+    - 快速排序
+  - 选择排序
+    - 简单选择排序
+    - 堆排序
+  - 归并排序
+  - 基数排序
+- 外部排序
+  - 多路归并排序
diff --git a/ch7/README.md b/ch7/README.md
index 6f23300..eea41c0 100644
--- a/ch7/README.md
+++ b/ch7/README.md
@@ -6,172 +6,16 @@
 
 ![查找基本概念2](concept2.png)
 
-## 2. 顺序查找
+## 2. [顺序查找](sequential-search/README.md#顺序查找)
 
-![顺序查找1](sequential-search1.png)
+## 3. [折半查找](binary-search/README.md#折半查找)
 
-![顺序查找2](sequential-search2.png)
+## 4. [分块查找](block-search/README.md#分块查找)
 
-![顺序查找3](sequential-search3.png)
+## 5. [B 树](b-tree/README.md#B-树)
 
-![顺序查找4](sequential-search4.png)
+## 6. [B+ 树](b-plus-tree/README.md#B+-树)
 
-![顺序查找5](sequential-search5.png)
-
-## 3. 折半查找
-
-![折半查找1](binary-search1.png)
-
-![折半查找2](binary-search2.png)
-
-![折半查找3](binary-search3.png)
-
-![折半查找4](binary-search4.png)
-
-![折半查找5](binary-search5.png)
-
-![折半查找6](binary-search6.png)
-
-![折半查找7](binary-search7.png)
-
-## 4. 分块查找
-
-![分块查找1](block-search1.png)
-
-![分块查找2](block-search2.png)
-
-![分块查找3](block-search3.png)
-
-![分块查找4](block-search4.png)
-
-![分块查找5](block-search5.png)
-
-## 5. B 树
-
-![B树1](b-tree1.png)
-
-![B树2](b-tree2.png)
-
-![B树3](b-tree3.png)
-
-![B树4](b-tree4.png)
-
-### 5.1. 插入
-
-![B树5](b-tree5.png)
-
-#### 5.1.1. 直接插入
-
-![B树6](b-tree6.png)
-
-#### 5.1.2. 向上分裂
-
-![B树7](b-tree7.png)
-
-![B树8](b-tree8.png)
-
-![B树9](b-tree9.png)
-
-![B树10](b-tree10.png)
-
-### 5.2. 删除
-
-![B树11](b-tree11.png)
-
-#### 5.2.1. 终端结点
-
-![B树12](b-tree12.png)
-
-- 直接删除。
-
-![B树13](b-tree13.png)
-
-- 兄弟够借。
-
-![B树14](b-tree14.png)
-
-![B树15](b-tree15.png)
-
-- 兄弟不够借。
-
-![B树16](b-tree16.png)
-
-![B树17](b-tree17.png)
-
-#### 5.2.2. 非终端结点
-
-![B树18](b-tree18.png)
-
-- 删除前驱节点的最大值。
-
-![B树19](b-tree19.png)
-
-![B树20](b-tree20.png)
-
-- 删除后继结点的最小值。
-
-![B树21](b-tree21.png)
-
-![B树22](b-tree22.png)
-
-- 合并子结点。
-
-![B树23](b-tree23.png)
-
-![B树24](b-tree24.png)
-
-## 6. B+ 树
-
-> 考研中对 B+ 树之考查定义；对 B 树既考察定义，也考察操作。
-
-![B+树1](b-plus-tree1.png)
-
-![B+树2](b-plus-tree2.png)
-
-![B+树3](b-plus-tree3.png)
-
-![B+树4](b-plus-tree4.png)
-
-## 7. 散列表
-
-### 7.1. 基本概念
-
-![散列表1](hash-table1.png)
-
-### 7.2. 散列函数
-
-![散列表2](hash-table2.png)
-
-![散列表3](hash-table3.png)
-
-![散列表4](hash-table4.png)
-
-![散列表5](hash-table5.png)
-
-![散列表6](hash-table6.png)
-
-### 7.3. 冲突处理
-
-![散列表7](hash-table7.png)
-
-![散列表8](hash-table8.png)
-
-![散列表9](hash-table9.png)
-
-![散列表10](hash-table10.png)
-
-![散列表11](hash-table11.png)
-
-![散列表12](hash-table12.png)
-
-![散列表13](hash-table13.png)
-
-![散列表14](hash-table14.png)
-
-![散列表15](hash-table15.png)
-
-### 7.4. 性能分析
-
-![散列表16](hash-table16.png)
+## 7. [散列表](hash-table/README.md#散列表)
 
 ![散列表17](hash-table17.png)
diff --git a/ch7/b-plus-tree/README.md b/ch7/b-plus-tree/README.md
new file mode 100644
index 0000000..fc4ff3d
--- /dev/null
+++ b/ch7/b-plus-tree/README.md
@@ -0,0 +1,11 @@
+# B+ 树
+
+> 考研中对 B+ 树之考查定义；对 B 树既考察定义，也考察操作。
+
+![B+树1](b-plus-tree1.png)
+
+![B+树2](b-plus-tree2.png)
+
+![B+树3](b-plus-tree3.png)
+
+![B+树4](b-plus-tree4.png)
diff --git a/ch7/b-plus-tree1.png b/ch7/b-plus-tree/b-plus-tree1.png
similarity index 100%
rename from ch7/b-plus-tree1.png
rename to ch7/b-plus-tree/b-plus-tree1.png
diff --git a/ch7/b-plus-tree2.png b/ch7/b-plus-tree/b-plus-tree2.png
similarity index 100%
rename from ch7/b-plus-tree2.png
rename to ch7/b-plus-tree/b-plus-tree2.png
diff --git a/ch7/b-plus-tree3.png b/ch7/b-plus-tree/b-plus-tree3.png
similarity index 100%
rename from ch7/b-plus-tree3.png
rename to ch7/b-plus-tree/b-plus-tree3.png
diff --git a/ch7/b-plus-tree4.png b/ch7/b-plus-tree/b-plus-tree4.png
similarity index 100%
rename from ch7/b-plus-tree4.png
rename to ch7/b-plus-tree/b-plus-tree4.png
diff --git a/ch7/b-tree/README.md b/ch7/b-tree/README.md
new file mode 100644
index 0000000..44e60a5
--- /dev/null
+++ b/ch7/b-tree/README.md
@@ -0,0 +1,73 @@
+# B 树
+
+![B树1](b-tree1.png)
+
+![B树2](b-tree2.png)
+
+![B树3](b-tree3.png)
+
+![B树4](b-tree4.png)
+
+## 1. 插入
+
+![B树5](b-tree5.png)
+
+### 1.1. 直接插入
+
+![B树6](b-tree6.png)
+
+### 1.2. 向上分裂
+
+![B树7](b-tree7.png)
+
+![B树8](b-tree8.png)
+
+![B树9](b-tree9.png)
+
+![B树10](b-tree10.png)
+
+## 2. 删除
+
+![B树11](b-tree11.png)
+
+### 2.1. 终端结点
+
+![B树12](b-tree12.png)
+
+- 直接删除。
+
+![B树13](b-tree13.png)
+
+- 兄弟够借。
+
+![B树14](b-tree14.png)
+
+![B树15](b-tree15.png)
+
+- 兄弟不够借。
+
+![B树16](b-tree16.png)
+
+![B树17](b-tree17.png)
+
+### 2.2. 非终端结点
+
+![B树18](b-tree18.png)
+
+- 删除前驱节点的最大值。
+
+![B树19](b-tree19.png)
+
+![B树20](b-tree20.png)
+
+- 删除后继结点的最小值。
+
+![B树21](b-tree21.png)
+
+![B树22](b-tree22.png)
+
+- 合并子结点。
+
+![B树23](b-tree23.png)
+
+![B树24](b-tree24.png)
diff --git a/ch7/b-tree1.png b/ch7/b-tree/b-tree1.png
similarity index 100%
rename from ch7/b-tree1.png
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diff --git a/ch7/binary-search/README.md b/ch7/binary-search/README.md
new file mode 100644
index 0000000..7424f6e
--- /dev/null
+++ b/ch7/binary-search/README.md
@@ -0,0 +1,15 @@
+# 折半查找
+
+![折半查找1](binary-search1.png)
+
+![折半查找2](binary-search2.png)
+
+![折半查找3](binary-search3.png)
+
+![折半查找4](binary-search4.png)
+
+![折半查找5](binary-search5.png)
+
+![折半查找6](binary-search6.png)
+
+![折半查找7](binary-search7.png)
diff --git a/ch7/binary-search1.png b/ch7/binary-search/binary-search1.png
similarity index 100%
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diff --git a/ch7/block-search/README.md b/ch7/block-search/README.md
new file mode 100644
index 0000000..603eb01
--- /dev/null
+++ b/ch7/block-search/README.md
@@ -0,0 +1,11 @@
+# 分块查找
+
+![分块查找1](block-search1.png)
+
+![分块查找2](block-search2.png)
+
+![分块查找3](block-search3.png)
+
+![分块查找4](block-search4.png)
+
+![分块查找5](block-search5.png)
diff --git a/ch7/block-search1.png b/ch7/block-search/block-search1.png
similarity index 100%
rename from ch7/block-search1.png
rename to ch7/block-search/block-search1.png
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diff --git a/ch7/hash-table/README.md b/ch7/hash-table/README.md
new file mode 100644
index 0000000..ee130d7
--- /dev/null
+++ b/ch7/hash-table/README.md
@@ -0,0 +1,41 @@
+# 散列表
+
+## 1. 基本概念
+
+![散列表1](hash-table1.png)
+
+## 2. 散列函数
+
+![散列表2](hash-table2.png)
+
+![散列表3](hash-table3.png)
+
+![散列表4](hash-table4.png)
+
+![散列表5](hash-table5.png)
+
+![散列表6](hash-table6.png)
+
+## 3. 冲突处理
+
+![散列表7](hash-table7.png)
+
+![散列表8](hash-table8.png)
+
+![散列表9](hash-table9.png)
+
+![散列表10](hash-table10.png)
+
+![散列表11](hash-table11.png)
+
+![散列表12](hash-table12.png)
+
+![散列表13](hash-table13.png)
+
+![散列表14](hash-table14.png)
+
+![散列表15](hash-table15.png)
+
+## 4. 性能分析
+
+![散列表16](hash-table16.png)
diff --git a/ch7/hash-table1.png b/ch7/hash-table/hash-table1.png
similarity index 100%
rename from ch7/hash-table1.png
rename to ch7/hash-table/hash-table1.png
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+# 顺序查找
+
+![顺序查找1](sequential-search1.png)
+
+![顺序查找2](sequential-search2.png)
+
+![顺序查找3](sequential-search3.png)
+
+![顺序查找4](sequential-search4.png)
+
+![顺序查找5](sequential-search5.png)
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+# 排序
+
+## 基本概念