diff --git a/DataStructure/DS_3_String/DS_3_0_SString.cpp b/DataStructure/DS_3_String/DS_3_0_SString.cpp
index ff09f58..aaed6bd 100644
--- a/DataStructure/DS_3_String/DS_3_0_SString.cpp
+++ b/DataStructure/DS_3_String/DS_3_0_SString.cpp
@@ -10,55 +10,164 @@
 typedef struct {
     char ch[MAXLEN];//每个分量存储一个字符
     int length; //串的实际长度
-}SString;
+} SString;
 
-bool InitStr(){
+bool InitStr() {
 
 }
 
 //求子串
-bool SubString(SString &Sub,SString S,int pos,int len){
-    if (pos+len-1>S.length)return false;
-    for (int i = pos; i < pos+len; ++i)
-        Sub.ch[i-pos+1]=S.ch[i];
-    Sub.length=len;
+bool SubString(SString &Sub, SString S, int pos, int len) {
+    if (pos + len - 1 > S.length)return false;
+    for (int i = pos; i < pos + len; ++i)
+        Sub.ch[i - pos + 1] = S.ch[i];
+    Sub.length = len;
     return true;
 }
 
 //比较操作，若S>T,则返回值>0;若S=T,则返回值=0；若S<T，则返回值<0;
-int StrCompare(SString S,SString T){
-    for (int i = 1; i <=S.length&i<=T.length; i++) {
-        if (S.ch[i]!=T.ch[i])
-            return S.ch[i]-T.ch[i];
+int StrCompare(SString S, SString T) {
+    for (int i = 1; i <= S.length & i <= T.length; i++) {
+        if (S.ch[i] != T.ch[i])
+            return S.ch[i] - T.ch[i];
     }
     //扫描过的所有字符都相同，则长度长的串更大
-    return S.length-T.length;
+    return S.length - T.length;
 }
 
 //获取字符串长度
-int StrLength(SString S){
+int StrLength(SString S) {
     return S.length;
 }
 
 //定位操作,若主串S中存在与串T值相同的子串，则返回它在主串S中第一次出现的位置，否则函数值为0；
-int Index(SString S,SString T){
-    int i=1,n=StrLength(S),m=StrLength(T);
+int Index(SString S, SString T) {
+    int i = 1, n = StrLength(S), m = StrLength(T);
     SString sub;
-    while(i<=n-m+1){
-        SubString(sub,S,i,m);
-        if (StrCompare(sub,T)!=0)++i;
+    while (i <= n - m + 1) {
+        SubString(sub, S, i, m);
+        if (StrCompare(sub, T) != 0)++i;
         else return i;//返回子串在主串中的位置
     }
     return 0;//S中不存在与T相等的子串
 }
-void TestStr(){
+
+//简单模式匹配
+int Index_Simple(SString S, SString T) {
+    int k = 1;//k记录当前主串指针
+    int i = k, j = 1;//j记录模式串指针，i记录主串中与模式串进行对比的子串的起始地址
+    while (i < S.length && j < T.length) {
+        if (S.ch[i] == T.ch[j]) {
+            ++i;
+            ++j;//继续比较后续字符
+        } else {
+            k++;//检查下一个字串
+            i = k;
+            j = 1;//重制j的值
+        }
+    }
+    if (j > T.length) {//匹配成功
+        return k;
+    } else {
+        return 0;
+    }
+}
+
+//简单模式匹配——王道教材写法
+int Index_Simple_CSKaoYan(SString S, SString T) {
+    int i = 1;//i记录当前主串指针
+    int j = 1;//j记录模式串指针
+    while (i < S.length && j < T.length) {
+        if (S.ch[i] == T.ch[j]) {
+            ++i;
+            ++j;//继续比较后续字符
+        } else {
+            i = i - j + 2; //检查下一个字串
+            j = 1;//重制j的值
+        }
+    }
+    if (j > T.length) {//匹配成功
+        return i - T.length;
+    } else {
+        return 0;
+    }
+}
+
+//KMP算法
+int Index_KMP(SString S, SString T, int next[]) {
+    int i = 1, j = 1;
+    while (i <= S.length && j <= T.length) {
+        if (j == 0 || S.ch[i] == T.ch[j]) {
+            ++i;
+            ++j;//继续比较后继字符
+        } else {
+            j = next[j];//模式串向右移动
+        }
+    }
+    if (j > T.length)//匹配成功
+        return i - T.length;
+    else
+        return 0;
+}
+
+//求模式串T的next数组
+void Get_Next(SString T, int next[]) {
+    int i = 1, j = 0;
+    next[1] = 0;
+    while (i < T.length) {
+        if (j == 0 || T.ch[i] == T.ch[j]) {
+            ++i;
+            ++j;
+            //如果pi=pj，则next[j+1]=next[j]+1
+            next[i] = j;
+        } else {
+            //否则令j=next[j],循环继续
+            j = next[j];
+        }
+    }
+}
+
+//KMP2
+int Index_KMP1(SString S, SString T) {
+    int i = 1, j = 1;
+    int next[T.length + 1];
+    Get_Next(T, next);
+    while (i <= S.length && j <= T.length) {
+        if (j == 0 || S.ch[i] == T.ch[j]) {
+            ++i;
+            ++j;//继续比较后继字符
+        } else {
+            j = next[j];//模式串向右移动
+        }
+    }
+    if (j > T.length)//匹配成功
+        return i - T.length;
+    else
+        return 0;
+}
+
+//优化next数组
+void Get_BetterNext(SString T, int betterNext[]) {
+    int i = 1, j = 0;
+    int next[T.length + 1];
+    Get_Next(T, next);//先求出next数组
+    betterNext[1] = 0;//令betterNext[1]=0
+    for (int j = 2; j <= T.length; ++j) {
+        if (T.ch[next[j]] == T.ch[j])
+            betterNext[j] = betterNext[next[j]];//这里涉及三个数组的对比，仔细看看
+        else
+            betterNext[j] = next[j];
+    }
+}
+
+void TestStr() {
     printf("开始测试！\n");
 
     printf("测试结束!\n");
 }
 
-int main(){
+int main() {
     TestStr();
-    return  0;
+    return 0;
 }
 
diff --git a/DataStructure/DS_3_String/DS_3_2_LString.cpp b/DataStructure/DS_3_String/DS_3_2_LString.cpp
index 60d2bee..a8f0e0c 100644
--- a/DataStructure/DS_3_String/DS_3_2_LString.cpp
+++ b/DataStructure/DS_3_String/DS_3_2_LString.cpp
@@ -2,7 +2,7 @@
 // Created by kim yang on 2020/8/8.
 //
 
-//链式存储
+//链式存储——单结点单字符
 #include <stdio.h>
 
 typedef struct StringNode{
diff --git a/DataStructure/DS_3_String/DS_3_3_LString.cpp b/DataStructure/DS_3_String/DS_3_3_LString.cpp
index 3198159..53a4fd5 100644
--- a/DataStructure/DS_3_String/DS_3_3_LString.cpp
+++ b/DataStructure/DS_3_String/DS_3_3_LString.cpp
@@ -2,7 +2,7 @@
 // Created by kim yang on 2020/8/8.
 //
 
-//链式存储
+//链式存储——单结点多字符
 #include <stdio.h>
 
 typedef struct StringNode{
diff --git a/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_7_线索二叉树.md b/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_7_线索二叉树.md
index 87c3df9..923b1fd 100644
--- a/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_7_线索二叉树.md
+++ b/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_7_线索二叉树.md
@@ -1 +1,44 @@
 # 线索二叉树
+
+![image-20200810110140084](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810110140.png)
+
+## 二叉树的中序遍历序列存在的问题
+
+![image-20200810133755960](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810133756.png)
+
+**不能直接从指定结点开始中序遍历**
+
+## 中序线索二叉树
+
+![image-20200810134119656](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134119.png)
+
+### 线索二叉树的存储结构
+
+![image-20200810134318361](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134318.png)
+
+![image-20200810134401938](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134401.png)
+
+## 先序线索二叉树
+
+![image-20200810134451790](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134451.png)
+
+### 先序线索二叉树的存储结构
+
+![image-20200810134658200](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134658.png)
+
+## 后序线索二叉树
+
+![image-20200810134712565](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134712.png)
+
+### 后序线索二叉树的存储结构
+
+![image-20200810134733209](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134733.png)
+
+## 对比
+
+![image-20200810134806808](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134806.png)
+
+## 总结回顾
+
+![image-20200810134838622](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810134838.png)
+
diff --git a/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_8_二叉树的线索化.md b/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_8_二叉树的线索化.md
index b1ba80a..f01739f 100644
--- a/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_8_二叉树的线索化.md
+++ b/DataStructure/DS_4_TreeAndBinaryTree/Doc_4_8_二叉树的线索化.md
@@ -1,2 +1,11 @@
 # 二叉树的线索化
 
+![image-20200810105331721](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810105331.png)
+
+用土办法找到中序前驱
+
+![image-20200810134958011](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810135203.png)
+
+## 中序线索化
+
+![image-20200810135151257](https://cdn.jsdelivr.net/gh/KimYangOfCat/MyPicStorage/2021-CSPostgraduate-408/20200810135151.png)
\ No newline at end of file