diff --git a/group24/315863321/src/main/java/com/johnChnia/coding2017/basic/tree/BinarySearchTree.java b/group24/315863321/src/main/java/com/johnChnia/coding2017/basic/tree/BinarySearchTree.java
index a362c78734..aaf8ea4dca 100644
--- a/group24/315863321/src/main/java/com/johnChnia/coding2017/basic/tree/BinarySearchTree.java
+++ b/group24/315863321/src/main/java/com/johnChnia/coding2017/basic/tree/BinarySearchTree.java
@@ -1,126 +1,155 @@
 package com.johnChnia.coding2017.basic.tree;
 
-import com.johnChnia.coding2017.basic.queue.Queue;
+import java.util.List;
+import java.util.Objects;
+
+import static org.apache.commons.lang3.ObjectUtils.compare;
+import static org.apache.commons.lang3.ObjectUtils.max;
 
 /**
- * Created by john on 2017/3/13.
+ * Created by john on 2017/5/27.
+ * <p>
+ * 二叉树：每个节点最多只有两个分支--https://zh.wikipedia.org/wiki/%E4%BA%8C%E5%8F%89%E6%A0%91
+ * 二叉搜索树：https://zh.wikipedia.org/wiki/%E4%BA%8C%E5%85%83%E6%90%9C%E5%B0%8B%E6%A8%B9
  */
-public class BinarySearchTree {
-
-
-    /**
-     * The root node of tree.
-     */
-    public BstNode root;
+public class BinarySearchTree<T extends Comparable> {
 
-    private Queue q = new Queue();
+    BinaryTreeNode<T> root;
 
+    public BinarySearchTree(BinaryTreeNode<T> root) {
+        this.root = root;
+    }
 
-    private static class BstNode {
-        private int data;
-        private BstNode left;
-        private BstNode right;
+    public BinaryTreeNode<T> getRoot() {
+        return root;
+    }
 
-        @Override
-        public String toString() {
-            return String.valueOf(data);
+    public T findMin() {
+        if (Objects.nonNull(root)) {
+            BinaryTreeNode<T> node = root;
+            while (Objects.nonNull(node.getLeft())) {
+                node = node.getLeft();
+            }
+            return node.getData();
         }
+        return null;
     }
 
-    /**
-     * create an BinarySearchTree.
-     *
-     * @param root root node of tree
-     * @param data stored element
-     * @return binarySearchTree
-     */
-    public BstNode insert(BstNode root, int data) {
-        if (root == null) {
-            root = getNewBstNode(data);
-            if (this.root == null) {
-                this.root = root;
+    public T findMax() {
+        if (Objects.nonNull(root)) {
+            BinaryTreeNode<T> node = root;
+            while (Objects.nonNull(node.getRight())) {
+                node = node.getRight();
             }
-            return root;
-        }
-        if (data <= root.data) {
-            root.left = insert(root.left, data);
-        } else {
-            root.right = insert(root.right, data);
+            return node.getData();
         }
-        return root;
+        return null;
     }
 
-    private BstNode getNewBstNode(int data) {
-        BstNode node = new BstNode();
-        node.data = data;
-        node.left = null;
-        node.right = null;
-        return node;
+
+    public int height() {
+        if (Objects.nonNull(root)) {
+            return height(root);
+        }
+        return -1;
     }
 
     /**
-     * Returns the minimum value in the tree.
+     * Height of a node: Number of edges in longest path from the node to a leaf node
+     * Height of tree: Height of root
+     * Height of tree with 1 node: 0
+     * Depth of a node: Number of edges in path from root to that node
+     * 树的高度：max(leftTree，rightTree）+ 1
      *
-     * @param root root node of the tree。
-     * @return the minimum value in the tree
-     * @throws IllegalArgumentException if root is null.
+     * @return 树的高度。
      */
-    public int findMin(BstNode root) {
-        int min;
-        if (root == null) {
-            throw new IllegalArgumentException("tree is empty");
-        } else if (root.left == null) {
-            min = root.data;
-        } else {
-            min = findMin(root.left);
+    private int height(BinaryTreeNode<T> root) {
+        if (Objects.isNull(root)) {
+            return 0;
+        }
+        int lheight = height(root.getLeft());
+        int rheight = height(root.getRight());
+
+        return max(lheight, rheight) + 1;
+    }
+
+    public int size() {
+        if (Objects.nonNull(root)) {
+            return size(root);
         }
-        return min;
+        return -1;
     }
 
     /**
-     * Returns the maximum value in the tree.
+     * 参考：http://www.geeksforgeeks.org/write-a-c-program-to-calculate-size-of-a-tree/
+     * Size of a tree is the number of elements present in the tree.
+     * Size of a tree = Size of left subtree + 1 + Size of right subtree.
      *
-     * @param root root node of the tree。
-     * @return the maximum value in the tree
-     * @throws IllegalArgumentException if root is null.
+     * @return 树的节点个数。
      */
-    public int findMax(BstNode root) {
-        int max;
-        if (root == null) {
-            throw new IllegalArgumentException("tree is empty");
-        } else if (root.right == null) {
-            max = root.data;
-        } else {
-            max = findMax(root.right);
+    private int size(BinaryTreeNode<T> root) {
+        if (Objects.isNull(root)) {
+            return 0;
         }
-        return max;
+
+        return 1 + size(root.getLeft()) + size(root.getRight());
     }
 
 
+    public void remove(T e) {
+        if (Objects.nonNull(e)) {
+            remove(root, e);
+        }
+    }
+
     /**
-     * Traverse each node from left to right.
+     * http://www.geeksforgeeks.org/binary-search-tree-set-2-delete/
      *
-     * @param root root node of the tree
+     * @param root 根节点
+     * @param e    删除节点
      */
-    public void LevelOrder(BstNode root) {
-        if (root == null) {
-            return;
-        }
-        q.add(root);
-        while (!q.empty()) {
-            BstNode current = (BstNode) q.peek();
-            if (current.left != null) {
-                q.add(current.left);
-            }
-            if (current.right != null) {
-                q.add(current.right);
+    private BinaryTreeNode<T> remove(BinaryTreeNode<T> root, T e) {
+        int flag = compare(e, root.data);
+        if (flag > 0) {
+            root.right = remove(root.getRight(), e);
+        } else if (flag < 0) {
+            root.left = remove(root.getLeft(), e);
+        } else {
+            // 叶子节点
+            if (Objects.isNull(root.getLeft()) && Objects.isNull(root.getRight())) {
+                return null;
+            } else if (Objects.isNull(root.getLeft())) {  // 只有一个子节点
+                return root.getRight();
+            } else if (Objects.isNull(root.getRight())) {
+                return root.getLeft();
             }
-            q.remove();
+            //两个子节点
+            BinarySearchTree<T> temp = new BinarySearchTree<>(root.getRight());
+            T data = temp.findMin();
+            remove(root, data);
+            root.data = data;
         }
+        return root;
     }
 
-    public BstNode getRoot() {
-        return root;
+    public List<T> levelVisit() {
+
+        return null;
+    }
+
+    public boolean isValid() {
+        return false;
+    }
+
+    public T getLowestCommonAncestor(T n1, T n2) {
+        return null;
+
+    }
+
+    public List<T> getNodesBetween(T n1, T n2) {
+        return null;
     }
 
 }
+
+
diff --git a/group24/315863321/src/test/java/com/johnChnia/coding2017/basic/tree/BinarySearchTreeTest.java b/group24/315863321/src/test/java/com/johnChnia/coding2017/basic/tree/BinarySearchTreeTest.java
index 968d386717..1383a1e5c9 100644
--- a/group24/315863321/src/test/java/com/johnChnia/coding2017/basic/tree/BinarySearchTreeTest.java
+++ b/group24/315863321/src/test/java/com/johnChnia/coding2017/basic/tree/BinarySearchTreeTest.java
@@ -1,38 +1,66 @@
 package com.johnChnia.coding2017.basic.tree;
 
-import com.johnChnia.coding2017.basic.tree.BinarySearchTree;
+import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.junit.MatcherAssert.assertThat;
-
 /**
- * Created by john on 2017/3/14.
+ * Created by john on 2017/5/27.
  */
 public class BinarySearchTreeTest {
-
-    private BinarySearchTree bst;
+    BinarySearchTree<Integer> tree = null;
 
     @Before
     public void setUp() throws Exception {
-        bst = new BinarySearchTree();
-        bst.insert(bst.getRoot(), 10);
-        bst.insert(bst.getRoot(), 20);
-        bst.insert(bst.getRoot(), 9);
-        bst.insert(bst.getRoot(), 11);
-        bst.insert(bst.getRoot(), 12);
+        BinaryTreeNode<Integer> root = new BinaryTreeNode<Integer>(6);
+        root.left = new BinaryTreeNode<Integer>(2);
+        root.right = new BinaryTreeNode<Integer>(8);
+        root.left.left = new BinaryTreeNode<Integer>(1);
+        root.left.right = new BinaryTreeNode<Integer>(4);
+        root.left.right.left = new BinaryTreeNode<Integer>(3);
+        tree = new BinarySearchTree<Integer>(root);
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        tree = null;
+    }
+
+    @Test
+    public void testFindMin() {
+        Assert.assertEquals(1, tree.findMin().intValue());
+
     }
 
     @Test
-    public void testFindMin() throws Exception {
-        assertThat(bst.findMin(bst.getRoot()), equalTo(9));
+    public void testFindMax() {
+        Assert.assertEquals(8, tree.findMax().intValue());
+    }
+
+    @Test
+    public void testHeight() {
+        Assert.assertEquals(4, tree.height());
+    }
 
+    @Test
+    public void testSize() {
+        Assert.assertEquals(6, tree.size());
     }
 
     @Test
-    public void testFindMax() throws Exception {
-        assertThat(bst.findMax(bst.getRoot()), equalTo(20));
+    public void testRemoveLeaf() {
+        tree.remove(4);
+        BinaryTreeNode<Integer> root = tree.getRoot();
+        Assert.assertEquals(3, root.left.right.data.intValue());
+
     }
 
-}
\ No newline at end of file
+    @Test
+    public void testRemoveMiddleNode() {
+        tree.remove(2);
+        BinaryTreeNode<Integer> root = tree.getRoot();
+        Assert.assertEquals(3, root.left.data.intValue());
+        Assert.assertEquals(4, root.left.right.data.intValue());
+    }
+}