diff --git a/EXP/Exp06/README.md b/EXP/Exp06/README.md
index 6f15081c387605dc8649a6973540a6fc5998bb57..f89e0ce8c0963d558315dc328284fefbc4ea77c3 100644
--- a/EXP/Exp06/README.md
+++ b/EXP/Exp06/README.md
@@ -1,11 +1,11 @@
 ## 实验6作业代码
 ### 题目详情
 - A Bank Account Class
-	- [Account.java](./Exp/Exp06/Problem01/Account.java)
-	- [ManageAccounts](./Exp/Exp06/Problem01/ManageAccounts.java)
+	- [Account.java](./Problem01/Account.java)
+	- [ManageAccounts](./Problem01/ManageAccounts.java)
 - Representing Names
-	- [Name.java](./Exp/Exp06/Problem02/Name.java)
-    - [TestNamesName.java](./Exp/Exp06/Problem02/TestNames.java)
+	- [Name.java](./Problem02/Name.java)
+    - [TestNamesName.java](./Problem02/TestNames.java)
 
 ### 讨论和建议
 如果大家在查看过程中发现错误或不足之处，欢迎大家在[Issues](https://gitee.com/Samler/java-work/issues)中发表自己的见解，也欢迎大家在[Issues](https://gitee.com/Samler/java-work/issues)中进行讨论。
diff --git a/PTA/ProblemSet02/Problem02/Main02.java b/PTA/ProblemSet02/Problem02/Main.java
similarity index 88%
rename from PTA/ProblemSet02/Problem02/Main02.java
rename to PTA/ProblemSet02/Problem02/Main.java
index 0a63f2a484df3f16c80a63c26bf5721c56170ec9..5a94f1ed2135fff938897be19455e1e5df58b14c 100644
--- a/PTA/ProblemSet02/Problem02/Main02.java
+++ b/PTA/ProblemSet02/Problem02/Main.java
@@ -2,7 +2,7 @@ package ProblemSet02.Problem02;
 
 import java.util.Scanner;
 
-public class Main02 {
+public class Main {
 	public static void main(String[] args) {
 		Scanner scan = new Scanner(System.in);
 		
diff --git a/PTA/ProblemSet03/Problem04/Main04.java b/PTA/ProblemSet03/Problem04/Main.java
similarity index 94%
rename from PTA/ProblemSet03/Problem04/Main04.java
rename to PTA/ProblemSet03/Problem04/Main.java
index 773152d6d570eff573ea06d21cbf7d7f34b2267c..85f64769de4311fefa46f90eddf61813c83b14f1 100644
--- a/PTA/ProblemSet03/Problem04/Main04.java
+++ b/PTA/ProblemSet03/Problem04/Main.java
@@ -4,7 +4,7 @@ import java.util.Scanner;
 import java.util.Arrays;
 import java.util.Comparator;
 
-public class Main04 {
+public class Main {
 	public static void main(String[] args) {
 		Scanner scan = new Scanner(System.in);
 		int id_len = Integer.parseInt(scan.nextLine());
diff --git a/PTA/ProblemSet05/Problem01/Main.java b/PTA/ProblemSet05/Problem01/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..f9cfd5f53ebbc2b25eefea31d8847416478abdc3
--- /dev/null
+++ b/PTA/ProblemSet05/Problem01/Main.java
@@ -0,0 +1,22 @@
+package ProblemSet05.Problem01;
+
+public class Main {
+	public static void main(String[] args) {
+		System.out.println("车牌号码是" + getCode());
+	}
+	
+	public static String getCode() {
+		for(int i = 1; i <= 9; i++) {
+			for(int j = 1; j <= 9; j++) {
+				int code = i * 1100 + j * 11, 
+					item = (int) Math.sqrt(code);
+				
+				if(Math.pow(item, 2) == code && i != j) {
+					return Integer.toString(code);
+				}
+			}
+		}
+		
+		return null;
+	}
+}
diff --git a/PTA/ProblemSet05/Problem02/Main.java b/PTA/ProblemSet05/Problem02/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..c49fdb7945c308c47fd47368dc44ab04703e3572
--- /dev/null
+++ b/PTA/ProblemSet05/Problem02/Main.java
@@ -0,0 +1,27 @@
+package ProblemSet05.Problem02;
+
+import java.util.Scanner;
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		String str = scan.nextLine();
+		scan.close();
+		
+		System.out.println(isPalindrome(str, str.length(), 0) ? "yes" : "no");
+	}
+	
+	public static boolean isPalindrome(String str, int length, int offset) {
+		if (length < 2) return false;
+		
+		int middleIndex = length / 2,
+			fixOffset = (length % 2 == 0) ? 0 : 1;
+		//fixOffset用于修正偶数情况下偏移量不对称问题
+		
+		if(middleIndex + offset + fixOffset >= length) return true;
+		if(str.charAt(middleIndex + fixOffset + offset) == str.charAt(middleIndex - offset - 1))
+			return isPalindrome(str, length, ++offset);
+		
+		return false;
+	}
+}
diff --git a/PTA/ProblemSet05/Problem03/Main.java b/PTA/ProblemSet05/Problem03/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..6567e641382bb4541f2e36a88f3073b5b826fd37
--- /dev/null
+++ b/PTA/ProblemSet05/Problem03/Main.java
@@ -0,0 +1,23 @@
+package ProblemSet05.Problem03;
+
+import java.util.Scanner;
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int len = scan.nextInt();
+		int[] hArray = new int[len];
+		
+		for(int i = 0; i < len; i++)
+			hArray[i] = scan.nextInt();
+		scan.close();
+		
+		System.out.println(getMax(hArray, 0, hArray[0]));
+	}
+	
+	public static int getMax(int[] arr, int index, int max) {
+		if(index > arr.length - 1) return max;
+		
+		return getMax(arr, index + 1, arr[index] > max ? arr[index] : max);
+	}
+}
diff --git a/PTA/ProblemSet06/Problem01/Main.java b/PTA/ProblemSet06/Problem01/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..58ab523da37bc2084b4c4b35055909616e6158fa
--- /dev/null
+++ b/PTA/ProblemSet06/Problem01/Main.java
@@ -0,0 +1,47 @@
+package ProblemSet06.Problem01;
+
+import java.util.Arrays;
+import java.util.Scanner;
+
+class PersonSortable implements Comparable<PersonSortable>{
+	private String name;
+	private int age;
+	
+	public PersonSortable(String name, int age) {
+		this.name = name;
+		this.age = age;
+	}
+	
+	public String toString() {
+		return name + "-" + age;
+	}
+
+	public int compareTo(PersonSortable o) {
+		int nameCompareResult = this.name.compareTo(o.name);
+		if(nameCompareResult == 0)
+			return this.age - o.age;
+		
+		return nameCompareResult;
+	}
+}
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int len = Integer.parseInt(scan.nextLine());
+		PersonSortable[] pList = new PersonSortable[len];
+		
+		for(int i = 0; i < len; i++) {
+			String[] pData = scan.nextLine().split(" ");
+			pList[i] = new PersonSortable(pData[0], Integer.parseInt(pData[1]));
+		}
+		scan.close();
+		
+		Arrays.sort(pList);
+		for(PersonSortable p : pList)
+			System.out.println(p);
+		
+		System.out.println(Arrays.toString(PersonSortable.class.getInterfaces()));
+	}
+}
+
diff --git a/PTA/ProblemSet06/Problem02/Main.java b/PTA/ProblemSet06/Problem02/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..b3fafe60aa60d6669e6373d3187f2b0cc0ffba9b
--- /dev/null
+++ b/PTA/ProblemSet06/Problem02/Main.java
@@ -0,0 +1,76 @@
+package ProblemSet06.Problem02;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.Scanner;
+
+class PersonSortable2 {
+	private String name;
+	private int age;
+	
+	public PersonSortable2(String name, int age) {
+		this.name = name;
+		this.age = age;
+	}
+	
+	public String toString() {
+		return name + "-" + age;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public int getAge() {
+		return age;
+	}
+
+	public void setAge(int age) {
+		this.age = age;
+	}
+}
+
+class NameComparator implements Comparator<PersonSortable2> {
+	
+	public int compare(PersonSortable2 o1, PersonSortable2 o2) {
+		return o1.getName().compareTo(o2.getName());
+	}
+	
+}
+
+class AgeComparator implements Comparator<PersonSortable2> {
+
+	public int compare(PersonSortable2 o1, PersonSortable2 o2) {
+		return o1.getAge() - o2.getAge();
+	}
+	
+}
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int len = Integer.parseInt(scan.nextLine());
+		PersonSortable2[] pList = new PersonSortable2[len];
+		
+		for(int i = 0; i < len; i++) {
+			String[] pData = scan.nextLine().split(" ");
+			pList[i] = new PersonSortable2(pData[0], Integer.parseInt(pData[1]));
+		}
+		scan.close();
+		
+		Arrays.sort(pList, new NameComparator());
+		System.out.println("NameComparator:sort");
+		for(PersonSortable2 p : pList) System.out.println(p);
+		
+		Arrays.sort(pList, new AgeComparator());
+		System.out.println("AgeComparator:sort");
+		for(PersonSortable2 p : pList) System.out.println(p);
+		
+		System.out.println(Arrays.toString(NameComparator.class.getInterfaces()));
+		System.out.println(Arrays.toString(AgeComparator.class.getInterfaces()));
+	}
+}
diff --git a/PTA/ProblemSet06/Problem03/Main.java b/PTA/ProblemSet06/Problem03/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..113b9fef9ce8291c02a6d9cc1e2584421faf6a81
--- /dev/null
+++ b/PTA/ProblemSet06/Problem03/Main.java
@@ -0,0 +1,37 @@
+package ProblemSet06.Problem03;
+
+import java.util.Scanner;
+
+public class Main {
+	public static void main(String[] args) {
+		int[] arr = new int[5];
+		Scanner scan = new Scanner(System.in);
+		boolean continueListen = true;
+		
+		while(continueListen) {
+			String[] cmd = scan.nextLine().split(" ");
+			try {
+				switch(cmd[0]) {
+					case "arr":
+						arr[Integer.parseInt(cmd[1])] = 0;
+						break;
+					case "null":
+						throw new NullPointerException();
+					case "cast":
+						@SuppressWarnings("unused")
+						Integer tmp = (Integer)((Object) new String(""));
+						break;
+					case "num":
+						Integer.parseInt(cmd[1]);
+						break;
+					default:
+						continueListen = false;
+				}
+			} catch (Exception e) {
+				System.out.println(e);
+			}
+		}
+		
+		scan.close();
+	}
+}
diff --git a/PTA/ProblemSet06/Problem04/Main.java b/PTA/ProblemSet06/Problem04/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..46ca5c89b41239663fbd9dcf347de40243106440
--- /dev/null
+++ b/PTA/ProblemSet06/Problem04/Main.java
@@ -0,0 +1,24 @@
+package ProblemSet06.Problem04;
+
+import java.util.Scanner;
+import java.util.Arrays;
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int n = scan.nextInt();
+		int[] numArr = new int[n];
+		
+		for(int i = 0; i < n; i++) {
+			try {
+				numArr[i] = Integer.parseInt(scan.next());
+			} catch (Exception e) {
+				i--;
+				System.out.println(e);
+			}
+		}
+		scan.close();
+		
+		System.out.println(Arrays.toString(numArr));
+	}
+}
diff --git a/PTA/ProblemSet06/Problem05/Main.java b/PTA/ProblemSet06/Problem05/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..c3a394366642ee5c5bc50f4810825878beb693e2
--- /dev/null
+++ b/PTA/ProblemSet06/Problem05/Main.java
@@ -0,0 +1,49 @@
+package ProblemSet06.Problem05;
+
+import java.util.Scanner;
+
+class ArrayUtils {
+	public static double findMax(double[] arr, int begin, int end) throws IllegalArgumentException {
+		if(begin < 0) throw new IllegalArgumentException("begin:" + begin + " < 0");
+		else if(begin >= end) throw new IllegalArgumentException("begin:" + begin + " >= end:" + end);
+		else if(end > arr.length) throw new IllegalArgumentException("end:" + end + " > arr.length");
+		
+		double max = arr[begin];
+		for(int i = begin; i < end; i++) {
+			if(arr[i] > max) max = arr[i];
+		}
+		
+		return max;
+	}
+}
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int n = scan.nextInt();
+		double[] numArr = new double[n];
+		boolean continueLinsten = true;
+		
+		for(int i = 0; i < n; i++) numArr[i] = scan.nextInt();
+		
+		while(continueLinsten) {
+			try {
+				int n1 = scan.nextInt(), n2 = scan.nextInt();
+				System.out.println(ArrayUtils.findMax(numArr, n1, n2));
+			}
+			catch (IllegalArgumentException e) {
+				System.out.println(e);
+			}
+			catch (Exception e) {
+				continueLinsten = false;
+			}
+		}
+		scan.close();
+		
+		try {
+		     System.out.println(ArrayUtils.class.getDeclaredMethod("findMax", double[].class,int.class,int.class));
+		} catch (Exception e1) {
+			
+		} 
+	}
+}
diff --git a/PTA/ProblemSet06/Problem06/Main.java b/PTA/ProblemSet06/Problem06/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..6dd8c2998146fa770903906ac756164af23d175e
--- /dev/null
+++ b/PTA/ProblemSet06/Problem06/Main.java
@@ -0,0 +1,91 @@
+package ProblemSet06.Problem06;
+
+import java.util.Scanner;
+import java.util.NoSuchElementException;
+
+class IllegalNameException extends RuntimeException {
+	private static final long serialVersionUID = 3229322801946529935L;
+	
+	public IllegalNameException() {
+		super();
+	}
+	
+	public IllegalNameException(String msg) {
+		super(msg);
+	}
+	
+}
+
+class IllegalScoreException extends Exception{
+	private static final long serialVersionUID = 1059038683602760667L;
+	
+	public IllegalScoreException() {
+		super();
+	}
+	
+	public IllegalScoreException(String msg) {
+		super(msg);
+	}
+	
+}
+
+class Student {
+	private String name;
+	private int score;
+	
+	public String getName() {
+		return name;
+	}
+	
+	public void setName(String name) {
+		if(Character.isDigit(name.charAt(0))) throw new IllegalNameException("the first char of name must not be digit, name=" + name);
+			
+		this.name = name;
+	}
+	
+	public int getScore() {
+		return score;
+	}
+	
+	public void setScore(int score) {
+		this.score = score;
+	}
+	
+	public String toString() {
+		return "Student [name=" + name + ", score=" + score + "]";
+	}
+	
+	public int addScore(int score) throws IllegalScoreException {
+		int tmpScore = this.score + score;
+		if(tmpScore < 0 || tmpScore > 100) throw new IllegalScoreException("score out of range, score=" + tmpScore);
+		
+		this.score = tmpScore;
+		return this.score;
+	}
+	
+}
+
+public class Main {
+	public static void main(String[] args) {
+		Scanner scan = new Scanner(System.in);
+		
+		while(true) {
+			String cmd = scan.nextLine();
+			if ("new".equals(cmd)) {
+				try {
+					String[] sData = scan.nextLine().split(" ");
+					if(sData.length != 2) throw new NoSuchElementException();
+					
+					Student stu = new Student();
+					stu.setName(sData[0]);
+					stu.addScore(Integer.parseInt(sData[1]));
+					System.out.println(stu);
+				} catch (Exception e) {
+					System.out.println(e);
+				}
+			} else break;
+		}
+		scan.close();
+		System.out.println("scanner closed");
+	}
+}
diff --git a/PTA/README.md b/PTA/README.md
index 0d75bf9c4722be8495c79b8f48aa9f4bcd1c43aa..a8762020deeb5410c176915b5700ef4487574249 100644
--- a/PTA/README.md
+++ b/PTA/README.md
@@ -17,14 +17,29 @@
 	- [7-3 jmu-Java-03面向对象基础-03-形状](./ProblemSet04/Problem03/Main.java)
 	- [7-4 jmu-Java-03面向对象基础-05-覆盖](./ProblemSet04/Problem04/Main.java)
 	- [7-5 jmu-Java-03面向对象-06-继承覆盖综合练习-Person、Student、Employee、Company](./ProblemSet04/Problem05/Main.java)
+- 实验05
+	- [7-1 消失的车](./ProblemSet05/Problem01/Main.java)
+	- [7-2 判断回文](./ProblemSet05/Problem02/Main.java)
+	- [7-3 我是升旗手](./ProblemSet05/Problem03/Main.java)
+- 实验06
+	- [7-1 jmu-Java-04面向对象进阶-01-接口-Comparable](./ProblemSet06/Problem01/Main.java)
+	- [7-2 jmu-Java-04面向对象进阶--02-接口-Comparator](./ProblemSet06/Problem02/Main.java)
+	- [7-3 jmu-Java-06异常-01-常见异常](./ProblemSet06/Problem03/Main.java)
+	- [7-4 jmu-Java-06异常-02-使用异常机制处理异常输入](./ProblemSet06/Problem04/Main.java)
+	- [7-5 jmu-Java-06异常-03-throw与throws](./ProblemSet06/Problem05/Main.java)
+	- [7-6 jmu-Java-06异常-04-自定义异常(综合)](./ProblemSet06/Problem06/Main.java)
+
 
 - 天梯题集（贡献者：[@small_lin168](https://gitee.com/small_lin168)）
+	- [7-1 N个数求和](./Tianti/Problem01/Main.java)
 	- [7-2 比较大小](./Tianti/Problem02/Main.java)
 	- [7-3 计算指数](./Tianti/Problem03/Main.java)
 	- [7-4 计算阶乘和](./Tianti/Problem04/Main.java)
 	- [7-5 简单题](./Tianti/Problem05/Main.java)
 	- [7-6 跟奥巴马一起画方块](./Tianti/Problem06/Main.java)
 	- [7-7 查验身份证](./Tianti/Problem07/Main.java)
+	- [7-10 树的遍历](./Tianti/Problem08/Main.java)
+	- [7-12 最长对称子串](./Tianti/Problem09/Main.java)
 
 ### 讨论和建议
 如果大家在查看过程中发现错误或不足之处，欢迎大家在[Issues](https://gitee.com/Samler/java-work/issues)中发表自己的见解，也欢迎大家在[Issues](https://gitee.com/Samler/java-work/issues)中进行讨论。
diff --git a/PTA/Tianti/Problem01/.keep b/PTA/Tianti/Problem01/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/PTA/Tianti/Problem01/Main.java b/PTA/Tianti/Problem01/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..41bbe8d57915e4763f0f1781252b438708e1fcf0
--- /dev/null
+++ b/PTA/Tianti/Problem01/Main.java
@@ -0,0 +1,67 @@
+package  Tianti.Problem01;
+ 
+import java.util.Scanner;
+ 
+public class Main {
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		int n = sc.nextInt();
+		
+		//输入完n之后将光标移到一下行
+		sc.nextLine();
+		int a, b;
+		
+		String str=sc.nextLine();
+//		System.out.println("This is:"+str);
+		String[] split = str.split(" ");
+		String s = split[0];
+		//获取分子
+		a = Integer.parseInt(s.substring(0, s.indexOf('/')));
+		//获取分母
+		b = Integer.parseInt(s.substring(s.indexOf('/') + 1));
+		int x, y, common;
+		
+		common = gcd(a, b);
+		a /= common;
+		b /= common;
+		
+		for (int i = 1; i < n; i++) {
+			s = split[i];
+			x = Integer.parseInt(s.substring(0, s.indexOf('/')));
+			y = Integer.parseInt(s.substring(s.indexOf('/') + 1));
+			
+			common = y * b / gcd(y, b);
+			
+			a *= common / b;
+			x *= common / y;
+ 
+			a += x;
+			b = common;
+			
+			common = gcd(a, b);
+			a /= common;
+			b /= common;
+			
+		}
+		
+		if(a / b != 0) {
+			if(a % b != 0) 
+				System.out.println(a / b + " " + a % b + "/" + b);
+			else
+				System.out.println(a / b);
+		} else {
+			if(a % b != 0) 
+				System.out.println(a % b + "/" + b);
+			else
+				System.out.println(0);
+		}
+	}
+	
+	private static int gcd(int a, int b) {
+		if(b==0){
+			return a;
+		}else{
+			return gcd(b,a%b);
+		}
+	}
+}
\ No newline at end of file
diff --git a/PTA/Tianti/Problem08/.keep b/PTA/Tianti/Problem08/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/PTA/Tianti/Problem08/Main.java b/PTA/Tianti/Problem08/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..c6abf00c57b9f85059c9d6a4c68d2582fc014bd2
--- /dev/null
+++ b/PTA/Tianti/Problem08/Main.java
@@ -0,0 +1,42 @@
+package Tianti.Problem08;
+ 
+import java.util.*;
+ 
+public class Pta8 {
+	//存储后序遍历结点
+    private static Vector<Integer> post = new Vector<>();
+    //存储中序遍历结点
+    private static Vector<Integer> in = new Vector<>();
+    //有序/LinkedHashMap
+    private static TreeMap<Integer,Integer> level = new TreeMap<>();
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        for(int i = 0; i<n; i++){
+        	post.add(sc.nextInt());
+        }
+        for(int i = 0; i<n; i++){
+        	in.add(sc.nextInt());
+        }
+        pre(n-1,0,n-1,0);
+        Set set = level.entrySet();//存储层序遍历结点
+        Iterator it = set.iterator();//开始输出层序遍历结点
+        Map.Entry entry = (Map.Entry)it.next();
+        System.out.print((Integer)entry.getValue());
+        while(it.hasNext()){
+            entry = (Map.Entry)it.next();
+            System.out.print(" "+(Integer)entry.getValue());
+        }
+    }
+ 
+    private static void pre(int root, int start, int end, int index) {
+        if(start > end)return;
+        int i = start;
+        while(i < end && in.get(i) != post.get(root)){
+        	i++;
+        }
+        level.put(index,post.get(root));//根
+        pre(root - 1 - end + i, start, i - 1, 2 * index + 1);//左
+        pre(root - 1, i + 1, end, 2 * index + 2);//右
+    }
+}
\ No newline at end of file
diff --git a/PTA/Tianti/Problem09/.keep b/PTA/Tianti/Problem09/.keep
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/PTA/Tianti/Problem09/Main.java b/PTA/Tianti/Problem09/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..ee6c6d2050c86c6435273804e90762b38e2858ca
--- /dev/null
+++ b/PTA/Tianti/Problem09/Main.java
@@ -0,0 +1,36 @@
+package Tianti.Problem09;
+ 
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+ 
+public class Pta9 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+        String str = reader.readLine();
+        //设置一个NN的二维数组
+        int arr_i[][] = new int[str.length()][str.length()];
+        int res_count =0;
+        for(int i=0;i<str.length();i++){
+            for(int j=0;j<=i;j++){
+                if(i==j){
+                	arr_i[j][i] = 1;
+                }else if(i-j==1){
+                    if(str.charAt(i)==str.charAt(j)){
+                    	arr_i[j][i] = 2;
+                    }
+                }else if(i-j>=2){
+                    if(str.charAt(i)==str.charAt(j)&&arr_i[j+1][i-1]>0){
+                    	arr_i[j][i] = arr_i[j+1][i-1]+2;
+                    }
+                }
+            }
+        }
+        for(int i=0;i<arr_i.length;i++){
+            for(int j=0;j<arr_i[0].length;j++){
+            	res_count = Math.max(res_count, arr_i[i][j]);
+            }
+        }
+        System.out.println(res_count);
+    }
+}
\ No newline at end of file
diff --git a/README.md b/README.md
index 412fac3bdf35e00cb9837f3a75d8a7eeea663e35..e516270e36d6a695d2d0544f884e50442a565354 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 
 ### 作业查看入口
 - PTA作业：[/PTA](/PTA)
-- 实验作业（待整理）：[/EXP](/EXP)
+- 实验作业（待完善）：[/EXP](/EXP)
 
 	由于前期未进行作业的整理，因此早前的部分作业代码可能没有放上来，敬请谅解。