diff --git a/src/main/java/com/cool/hot100/binary_tree/Num105.java b/src/main/java/com/cool/hot100/binary_tree/Num105.java
new file mode 100644
index 0000000..59f8868
--- /dev/null
+++ b/src/main/java/com/cool/hot100/binary_tree/Num105.java
@@ -0,0 +1,57 @@
+package com.cool.hot100.binary_tree;
+
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/01/19:34
+ * DayNumber 2
+ * Hard 2
+ * Level 5
+ */
+public class Num105 {
+
+    Map<Integer, Integer> map = new HashMap<>();
+
+    public TreeNode buildTree(int[] preorder, int[] inorder) {
+        for (int i = 0; i < inorder.length; i++) {
+            map.put(inorder[i], i);
+        }
+        return buildTree(preorder, 0, 0, inorder.length - 1);
+    }
+
+    public TreeNode buildTree(int[] preorder, int indexInPre, int startInIn, int endInIn) {
+        if (startInIn > endInIn) return null;
+        TreeNode node = new TreeNode(preorder[indexInPre]);
+        Integer headInIn = map.get(preorder[indexInPre]);
+        int leftLength = headInIn - startInIn;
+        int rightLength = endInIn - headInIn;
+        node.left = buildTree(preorder,indexInPre+1,startInIn,headInIn-1);
+        node.right=buildTree(preorder,indexInPre+leftLength+1,headInIn+1,endInIn);
+        return node;
+    }
+
+    @Test
+    public void test() {
+//        TreeNode node1 = new TreeNode(6);
+//        TreeNode node2 = new TreeNode(2);
+//        TreeNode node3 = new TreeNode(4);
+//        TreeNode node4 = new TreeNode(3);
+//        TreeNode node5 = new TreeNode(5);
+//        TreeNode node6 = new TreeNode(2);
+//        TreeNode node7 = new TreeNode(1);
+//        node7.left = node6;
+//        node7.right = node5;
+//        node6.left = node4;
+//        node6.right = node3;
+//        node5.right = node1;
+        buildTree(new int[]{3, 9, 20, 15, 7}, new int[]{9, 3, 15, 20, 7});
+    }
+}
+
+
diff --git a/src/main/java/com/cool/hot100/binary_tree/Num114.java b/src/main/java/com/cool/hot100/binary_tree/Num114.java
new file mode 100644
index 0000000..6b62128
--- /dev/null
+++ b/src/main/java/com/cool/hot100/binary_tree/Num114.java
@@ -0,0 +1,69 @@
+package com.cool.hot100.binary_tree;
+
+import org.junit.Test;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/01/17:17
+ * DayNumber 1
+ * Hard 2
+ * Level 3
+ */
+public class Num114 {
+    public void flatten(TreeNode root) {
+//        while (root != null) {
+//            TreeNode right = root.right;
+//            if (root.left != null) {
+//                TreeNode left = root.left;
+//                while (left.right != null) {
+//                    left = left.right;
+//                }
+//                root.right = root.left;
+//                left.right = right;
+//            }
+//            root.left = null;
+//            root = root.right;
+//        }
+        dfs(root);
+    }
+
+    private TreeNode dfs(TreeNode root) {
+        if (root == null) return null;
+        TreeNode returnRoot = root;
+        TreeNode right = dfs(root.right);
+        TreeNode left = dfs(root.left);
+        root.left = null;
+        if (left != null) {
+            root.right = left;
+        }
+        if (left != null && right != null) {
+            while (root.right!=null){
+                root=root.right;
+            }
+            root.right = right;
+        } else if (right != null) {
+            root.right = right;
+        }
+        return returnRoot;
+    }
+
+    @Test
+    public void test() {
+        TreeNode node1 = new TreeNode(6);
+        TreeNode node2 = new TreeNode(2);
+        TreeNode node3 = new TreeNode(4);
+        TreeNode node4 = new TreeNode(3);
+        TreeNode node5 = new TreeNode(5);
+        TreeNode node6 = new TreeNode(2);
+        TreeNode node7 = new TreeNode(1);
+        node7.left = node6;
+        node7.right = node5;
+        node6.left = node4;
+        node6.right = node3;
+        node5.right = node1;
+        flatten(node7);
+    }
+
+}
diff --git a/src/main/java/com/cool/hot100/binary_tree/Num199.java b/src/main/java/com/cool/hot100/binary_tree/Num199.java
index 9a8b228..c80c803 100644
--- a/src/main/java/com/cool/hot100/binary_tree/Num199.java
+++ b/src/main/java/com/cool/hot100/binary_tree/Num199.java
@@ -1,6 +1,5 @@
 package com.cool.hot100.binary_tree;
 
-import sun.reflect.generics.tree.Tree;
 
 import java.util.ArrayList;
 import java.util.LinkedList;