diff --git a/README.md b/README.md
index 27df5ebe65f2aeb31dba3ce3d49dcfc69340d96e..37a780a304f909ee4948d91aaee9540de52dd4e5 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,4 @@
 
 #### Tips
 若需要上传其他有帮助的项目或者文件请在shared分支进行操作，否则一律不允许通过哦，谢谢配合！！！
+>>>>>>> master
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta1.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta1.java"
new file mode 100644
index 0000000000000000000000000000000000000000..133b6e30d79db47164ade433bc682c8b3b747ab6
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta1.java"
@@ -0,0 +1,54 @@
+package tianti;
+
+import java.util.Scanner;
+
+public class Pta1 {
+
+	static int gcd(int a, int b) {
+		if (b == 0)
+			return a;
+		else
+			return gcd(b, a % b);
+	}
+
+	static int lcm(int a, int b) {
+		return a * b / gcd(a, b);
+	}
+	
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner sc = new Scanner(System.in);
+		int n = sc.nextInt();
+		int a, b, ta = 0, tb = 0;
+		for (int i = 1; i <= n; i++) {
+			String str = sc.next();
+			a = Integer.parseInt(str.split("/")[0]);
+			b = Integer.parseInt(str.split("/")[1]);
+			if (i == 1) {
+				ta = a;
+				tb = b;
+			} else {
+				int sb;
+				sb = lcm(b, tb);// �����������
+				// ���������ϲ�
+				ta = sb / tb * ta + sb / b * a;
+				tb = sb;
+			}
+			// ��������
+			int g = gcd(Math.abs(ta), Math.abs(tb));
+			ta = ta / g;
+			tb = tb / g;
+		}
+		if (ta == 0 || Math.abs(ta) >= tb) {
+			System.out.print(ta / tb + " ");
+			if (ta % tb == 0) {
+				System.out.println();
+			} else {
+				System.out.println("" + (Math.abs(ta) % tb) + "/" + tb + "");
+			}
+		} else {
+			System.out.println("" + ta + "/" + tb + "");
+		}
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta2.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta2.java"
new file mode 100644
index 0000000000000000000000000000000000000000..9063eda7f5bf5be4ece1edc5b7fb36ccec53f24c
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta2.java"
@@ -0,0 +1,24 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class Main {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner sc=new Scanner(System.in);
+		int N=3;
+		int[] sort_result=new int[N];
+		for(int i =0;i<N;i++){
+			sort_result[i]=sc.nextInt();
+		}
+		Arrays.sort(sort_result);
+		for(int i=0;i<N;i++){
+			if(i==N-1){
+				System.out.print(sort_result[i]);
+				break;
+			}
+			System.out.print(sort_result[i]+"->");
+		}
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta3.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta3.java"
new file mode 100644
index 0000000000000000000000000000000000000000..77780a5a119cc6b68f7434010e14a7f55d082972
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta3.java"
@@ -0,0 +1,13 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class Main {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner sc=new Scanner(System.in);
+		int N=sc.nextInt();
+		System.out.println("2^"+N+" = "+(int)Math.pow(2, N));
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta4.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta4.java"
new file mode 100644
index 0000000000000000000000000000000000000000..492966cbd0ddacb65549e5fff1a71b93f9120de3
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta4.java"
@@ -0,0 +1,27 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class Main {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner sc = new Scanner(System.in);
+		int N = sc.nextInt();
+		System.out.println(fib(N));
+	}
+
+	public static int fib(int N) {
+		int temp = 1;
+		int sum = 0;
+		for (int i = 1; i <= N; i++) {
+			if (N == 0) {
+				sum = 1;
+			} else {
+				temp *= i;
+				sum += temp;
+			}
+		}
+		return sum;
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta5.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta5.java"
new file mode 100644
index 0000000000000000000000000000000000000000..114280751421b42590a213a57bfada14cd6709cb
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta5.java"
@@ -0,0 +1,9 @@
+import java.util.Scanner;
+
+public class Main {
+
+	public static void main(String[] args) {
+		System.out.println("This is a simple problem.");
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta6.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta6.java"
new file mode 100644
index 0000000000000000000000000000000000000000..b6a08387819419be28363aa115e96ce596d5cd3d
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta6.java"
@@ -0,0 +1,26 @@
+package tianti;
+
+import java.util.Scanner;
+
+public class Pta6 {
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		double n = sc.nextInt(); // ����N���ַ�
+		String s = sc.next(); 		// �����ַ���ʽ
+		if (3 <= n && n <= 21) {
+			double h = n / 2; 		// ����߶�
+			int x = (int) (n / 2);	//��������
+			double y = h - x;
+			if (y >= 0.5) {
+				h++;
+			}
+			for (int i = 0; i < (int) h; i++) {  //ͨ���߶�����ӡ
+				for (int j = 0; j < n; j++) {	 //ͨ����������ӡ
+					System.out.print(s);
+				}
+				System.out.println();
+			}
+		}
+
+	}
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta7.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta7.java"
new file mode 100644
index 0000000000000000000000000000000000000000..996634a1b025b45bc91b0583e70f5ac7de80a7b2
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta7.java"
@@ -0,0 +1,49 @@
+package tianti;
+
+import java.util.Scanner;
+
+public class Pta7 {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+		// ���Լ�
+		// 350322111122334455
+		Scanner sc = new Scanner(System.in);
+		String[] Z = new String[] { "1", "2", "3", "4", "5", "6", "7", "8", "9", "10" };
+		char[] M = new char[] { '1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2' };
+		//Ȩ��
+		int[] pow = new int[] { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 };
+
+		int N = sc.nextInt();
+		char[][] id_spilt = new char[N][18];
+		int allpassed = 1;
+		// ��N������֤��������ά��
+		for (int i = 0; i < N; i++) {
+			String id_card = sc.next();
+			for (int j = 0; j < 18; j++) {
+				id_spilt[i][j] = Character.valueOf(id_card.charAt(j));
+			}
+		}
+		// �����ж�
+		for (int i = 0; i < N; i++) {
+			int z = 0;
+			for (int j = 0; j < 17; j++) {
+				z += ((id_spilt[i][j]) - '0') * pow[j];
+			}
+			//ȡģ
+			z %= 11;
+			if (M[z] != id_spilt[i][17]) {
+				allpassed = 0;
+				for (int k = 0; k < 18; k++) {
+					System.out.print(id_spilt[i][k]);
+				}
+				System.out.println();
+			}
+		}
+		if (allpassed == 1) {
+			System.out.println("All passed");
+		}
+	}
+
+}
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta8.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta8.java"
new file mode 100644
index 0000000000000000000000000000000000000000..d360ed6f3d3f646325df346cfbb566a704f08605
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta8.java"
@@ -0,0 +1,119 @@
+import java.util.*;
+
+public class Main {
+	
+	static String str="";
+	
+	class Node {
+		int data;
+		Node leftChild;
+		Node rightChild;
+
+		public Node(int idata) {
+			data = idata;
+		}
+	}
+
+	// 根节点
+	private Node root;
+
+	// 接受中序遍历数组和后序遍历数组，进入递归方法
+	Node reCreatTree(int[] mid, int[] last) {
+		root = reCreate(mid, 0, mid.length - 1, last, 0, last.length - 1);
+		return root;
+	}
+
+	// 参数依次为中序遍历数组，起始点，结束点；后序遍历数组，起始点，结束点
+	Node reCreate(int[] mid, int midStrat, int midEnd, int[] last, int lastStart, int lastEnd) {
+		// 防止前后交叉导致已选过的数值重复选中
+		if (lastStart > lastEnd) {
+			return null;
+		}
+		// 防止数组越界
+		if (lastStart < 0 || lastEnd < 0 || midStrat < 0 || midEnd < 0) {
+			return null;
+		}
+		// 给所选节点赋值
+		Node newNode = new Node(last[lastEnd]);
+		int index = IndexOfRootInMid(mid, newNode.data);
+		// 所选节点左子树的数量
+		int leftNum = index - midStrat;
+		// 向左子树往下走
+		newNode.leftChild = reCreate(mid, midStrat, index - 1, last, lastStart, lastStart + leftNum - 1);
+		// 向右子树往下走
+		newNode.rightChild = reCreate(mid, index + 1, midEnd, last, lastStart + leftNum, lastEnd - 1);
+		// 返回节点
+		return newNode;
+	}
+
+	// 获得所选子树的根节点在中序数组中的下标
+	int IndexOfRootInMid(int[] mid, int rootData) {
+		int index = -1;
+		for (int i = 0; i < mid.length - 1; i++) {
+			if (mid[i] == rootData) {
+				index = i;
+				break;
+			}
+		}
+		return index;
+	}
+
+	// 输出树
+	public void displayTree() {
+		Stack<Node> globalStack = new Stack<Node>();
+		globalStack.push(root);
+		int nBlanks = 32;
+		boolean isRowEmpty = false;
+		while (isRowEmpty == false) {
+			Stack<Node> localStack = new Stack<Node>();
+			isRowEmpty = true;
+
+			while (globalStack.isEmpty() == false) {
+				Node temp = (Node) globalStack.pop();
+				if (temp != null) {
+//						System.out.print(temp.data+" ");
+						str+=temp.data;
+						localStack.push(temp.leftChild);
+						localStack.push(temp.rightChild);
+						if (temp.leftChild != null || temp.rightChild != null)
+							isRowEmpty = false;
+				} else {
+					localStack.push(null);
+					localStack.push(null);
+				}
+				
+			}
+			nBlanks /= 2;
+			while (localStack.isEmpty() == false)
+				globalStack.push(localStack.pop());
+		}
+	}
+
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+//		System.out.println("请输入N：");
+		int N = sc.nextInt();
+		int[] preOrder = new int[N];
+		int[] inOrder = new int[N];
+		int[] postOrder = new int[N];
+//		System.out.println("请输入后序遍历：");
+		for (int i = 0; i < N; i++) {
+			postOrder[i] = sc.nextInt();
+		}
+//		System.out.println("请输入中序遍历：");
+		for (int i = 0; i < N; i++) {
+			inOrder[i] = sc.nextInt();
+		}
+		Main tree = new Main();
+		tree.reCreatTree(inOrder, postOrder);
+		tree.displayTree();
+//		System.out.println(str);
+		for(int i=0;i<str.length();i++){
+			if(i==str.length()-1){
+				System.out.print(str.substring(i,i+1));
+				break;
+			}
+			System.out.print(str.substring(i,i+1)+" ");
+		}
+	}
+}
\ No newline at end of file
diff --git "a/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta9.java" "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta9.java"
new file mode 100644
index 0000000000000000000000000000000000000000..c4c86e71af35058b7b327f6a87c8104480cf0324
--- /dev/null
+++ "b/\345\244\251\346\242\257\351\242\230\351\233\206\357\274\2101\357\274\211/Pta9.java"
@@ -0,0 +1,41 @@
+package tianti;
+
+import java.util.Scanner;
+
+public class Pta9 {
+
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		// Is PAT&TAP symmetric?
+		String str = sc.nextLine();
+		System.out.println(MaxSubStr(str) + "=" + MaxSubStr(str).length());
+
+	}
+
+	// �ж϶ԳƵķ���
+	public static boolean symmetric(String str) {
+		// ����char������б��� ��β�ͺ�ͷ��ͬʱ���бȽ�ȡ���Գ����IJ���
+		char[] c_arr = str.toCharArray();
+		int min = 0;
+		int max = c_arr.length - 1;
+		while (min < max) {
+			if (c_arr[min++] != c_arr[max--]){
+				return false;
+			}
+		}
+		return true;
+	}
+	
+	// ������Գ�����
+	public static String MaxSubStr(String str) {
+		String substr = "";
+		for (int i = 0; i < str.length(); i++) {
+			for (int j = str.length(); j >= i; j--) {
+				String temp = str.substring(i, j);
+				if (symmetric(temp) && temp.length() >= substr.length())
+					substr = temp;
+			}
+		}
+		return substr;
+	}
+}
\ No newline at end of file