diff --git a/group20/452472201/.gitignore b/group20/452472201/.gitignore
new file mode 100644
index 0000000000..ae3c172604
--- /dev/null
+++ b/group20/452472201/.gitignore
@@ -0,0 +1 @@
+/bin/
diff --git a/group20/452472201/src/com/coding/basic/ArrayList.java b/group20/452472201/src/com/coding/basic/ArrayList.java
new file mode 100644
index 0000000000..1af26ce934
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/ArrayList.java
@@ -0,0 +1,98 @@
+package com.coding.basic;
+
+public class ArrayList implements List {
+
+	private  int size=0;
+
+	private  Object[] elementData =new Object[10];
+
+
+	//数组扩容
+	private void  ensureCapacityInternal(){
+		if(size==elementData.length){
+			Object[] newArray = new Object[size*2];
+			System.arraycopy(elementData, 0, newArray, 0, elementData.length);
+			elementData=newArray;
+		}
+	}
+
+	public void add(Object o){
+		ensureCapacityInternal();
+		elementData[size]=o;
+		size++;
+	}
+
+	public void add(int index, Object o){
+		ensureCapacityInternal();
+		if(index<0){
+			try {
+				throw new Exception();
+			} catch (Exception e) {
+				e.printStackTrace();
+			}
+		}
+
+		System.arraycopy(elementData, index, elementData, index+1,size-index );
+        elementData[index]=o;
+        size++;
+	}
+
+	public Object get(int index){
+		if(index<0||index>=size){
+			try {
+				throw new Exception();
+			} catch (Exception e) {
+				e.printStackTrace();
+			}
+		}
+		return elementData[index];
+	}
+
+	public Object remove(int index){
+		if(index>=size){
+			try {
+				throw new Exception();
+			} catch (Exception e) {
+				e.printStackTrace();
+			}
+		}else{
+
+			int numMoved=size-index-1;
+			if(numMoved>0){
+				System.arraycopy(elementData, index+1, elementData, index, numMoved);
+			}
+
+			elementData[size--] = null;			
+		}
+		return index;
+
+	}
+
+
+	public int size(){
+		return size;
+	}
+
+
+	private class Iter implements Iterator {
+		//计数器 
+		private int coursor=-1;
+		//判断是否存在下一个
+		public boolean hasNext(){
+			return coursor+1<size;
+		}
+		//获取下一个
+		public String next(){
+			coursor++;
+			return (String) elementData[coursor];
+		}
+	}
+		public Iterator iterator(){
+
+			return new Iter();
+
+		}
+}
+
+
+
diff --git a/group20/452472201/src/com/coding/basic/BinaryTreeNode.java b/group20/452472201/src/com/coding/basic/BinaryTreeNode.java
new file mode 100644
index 0000000000..d7ac820192
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/BinaryTreeNode.java
@@ -0,0 +1,32 @@
+package com.coding.basic;
+
+public class BinaryTreeNode {
+	
+	private Object data;
+	private BinaryTreeNode left;
+	private BinaryTreeNode right;
+	
+	public Object getData() {
+		return data;
+	}
+	public void setData(Object data) {
+		this.data = data;
+	}
+	public BinaryTreeNode getLeft() {
+		return left;
+	}
+	public void setLeft(BinaryTreeNode left) {
+		this.left = left;
+	}
+	public BinaryTreeNode getRight() {
+		return right;
+	}
+	public void setRight(BinaryTreeNode right) {
+		this.right = right;
+	}
+	
+	public BinaryTreeNode insert(Object o){
+		return  null;
+	}
+	
+}
diff --git a/group20/452472201/src/com/coding/basic/Iterator.java b/group20/452472201/src/com/coding/basic/Iterator.java
new file mode 100644
index 0000000000..9c56ce26a3
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/Iterator.java
@@ -0,0 +1,9 @@
+package com.coding.basic;
+
+public interface Iterator {
+	public boolean hasNext();
+	public Object next();
+
+}
+
+ 
\ No newline at end of file
diff --git a/group20/452472201/src/com/coding/basic/LinkedList.java b/group20/452472201/src/com/coding/basic/LinkedList.java
new file mode 100644
index 0000000000..e2c4e5e795
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/LinkedList.java
@@ -0,0 +1,46 @@
+package com.coding.basic;
+
+public class LinkedList implements List {
+	
+	private Node head;
+	
+	public void add(Object o){
+		
+	}
+	public void add(int index , Object o){
+		
+	}
+	public Object get(int index){
+		return null;
+	}
+	public Object remove(int index){
+		return null;
+	}
+	
+	public int size(){
+		return -1;
+	}
+	
+	public void addFirst(Object o){
+		
+	}
+	public void addLast(Object o){
+		
+	}
+	public Object removeFirst(){
+		return null;
+	}
+	public Object removeLast(){
+		return null;
+	}
+	public Iterator iterator(){
+		return null;
+	}
+	
+	
+	private static  class Node{
+		Object data;
+		Node next;
+		
+	}
+}
diff --git a/group20/452472201/src/com/coding/basic/List.java b/group20/452472201/src/com/coding/basic/List.java
new file mode 100644
index 0000000000..10d13b5832
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/List.java
@@ -0,0 +1,9 @@
+package com.coding.basic;
+
+public interface List {
+	public void add(Object o);
+	public void add(int index, Object o);
+	public Object get(int index);
+	public Object remove(int index);
+	public int size();
+}
diff --git a/group20/452472201/src/com/coding/basic/Queue.java b/group20/452472201/src/com/coding/basic/Queue.java
new file mode 100644
index 0000000000..36e516e266
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/Queue.java
@@ -0,0 +1,19 @@
+package com.coding.basic;
+
+public class Queue {
+	
+	public void enQueue(Object o){		
+	}
+	
+	public Object deQueue(){
+		return null;
+	}
+	
+	public boolean isEmpty(){
+		return false;
+	}
+	
+	public int size(){
+		return -1;
+	}
+}
diff --git a/group20/452472201/src/com/coding/basic/Stack.java b/group20/452472201/src/com/coding/basic/Stack.java
new file mode 100644
index 0000000000..a5a04de76d
--- /dev/null
+++ b/group20/452472201/src/com/coding/basic/Stack.java
@@ -0,0 +1,22 @@
+package com.coding.basic;
+
+public class Stack {
+	private ArrayList elementData = new ArrayList();
+	
+	public void push(Object o){		
+	}
+	
+	public Object pop(){
+		return null;
+	}
+	
+	public Object peek(){
+		return null;
+	}
+	public boolean isEmpty(){
+		return false;
+	}
+	public int size(){
+		return -1;
+	}
+}