diff --git a/contest/src/main/java/com/github/contest/Execute.kt b/contest/src/main/java/com/github/contest/Execute.kt
index 88d6716..3fc8e85 100644
--- a/contest/src/main/java/com/github/contest/Execute.kt
+++ b/contest/src/main/java/com/github/contest/Execute.kt
@@ -1,9 +1,9 @@
 package com.github.contest
 
 
-import com.github.contest.binaryTree.findDuplicateSubtreesProdVariant
-import com.github.contest.binaryTree.printTree
+import com.github.contest.array.isTriangle
 import com.github.contest.binaryTree.toTreeNode
+import com.github.contest.binaryTree.tree2str
 import com.github.contest.math.numberOfPowerfulInt
 import com.github.contest.slidingWindow.customStructure.rabinKarpMultiPattern
 import com.github.contest.slidingWindow.customStructure.slidingWindowClassic
@@ -16,15 +16,20 @@ import java.util.TreeMap
  */
 
 fun main() {
-    val tree = listOf(1, 2, 3, 4, null, 2, 4, null, null, 4).toTreeNode()
-    //tree.printTree()
+    //largestPerimeter(intArrayOf(3, 2, 3, 10, 2, 1, 4, 4)).also { println(it) }
 
-    findDuplicateSubtreesProdVariant(tree).apply {
-        this.forEach {
-            it.printTree()
-        }
-    }
+    isTriangle(3, 4, 4).also { println(it) }
+}
 
+fun treeLaunch() {
+    val tree1 = listOf(1, 2, 3, 4).toTreeNode()
+    val tree2 = listOf(1).toTreeNode()
+    val tree3 = listOf(1, 2, 3, null, 4).toTreeNode()
+    //tree1.printTree()
+
+    tree2str(tree3).also {
+        println(it)
+    }
 }
 
 
diff --git a/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeLeetcode.kt b/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeLeetcode.kt
index 1b86f7b..60ad28f 100644
--- a/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeLeetcode.kt
+++ b/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeLeetcode.kt
@@ -402,6 +402,59 @@ fun findDuplicateSubtrees(root: TreeNode?): List<TreeNode?> {
 
 private fun serializeDuplicateSubTree(root: TreeNode?): String = when {
     root == null -> "null"
-    else -> "#${root.`val`} , ${serialize(root?.left)} , ${serialize(root?.right)}"
+    else -> "#${root.`val`} , ${serializeDuplicateSubTree(root?.left)} , ${
+        serializeDuplicateSubTree(
+            root?.right
+        )
+    }"
+}
+
+/**
+ * 606. Construct String from Binary Tree
+ */
+
+fun tree2str(root: TreeNode?): String {
+    root ?: return "()"
+
+    val leftCall = tree2str(root.left)
+    val rightCall = tree2str(root.right)
+    val pattern = "()"
+
+    return buildString {
+        when {
+            leftCall == pattern && rightCall == pattern -> append(root.`val`)
+            rightCall == pattern -> {
+                append(root.`val`)
+                append("(")
+                append(leftCall)
+                append(")")
+            }
+
+            else -> {
+                append(root.`val`)
+                append("(")
+                append(if (leftCall == pattern) "" else leftCall)
+                append(")")
+                append("(")
+                append(rightCall)
+                append(")")
+            }
+        }
+    }
+}
+
+
+/**
+ * 669. Trim a Binary Search Tree
+ */
+
+fun trimBST(root: TreeNode?, low: Int, high: Int): TreeNode? = when {
+    root == null -> null
+    root.`val` < low -> trimBST(root.right, low, high)
+    root.`val` > high -> trimBST(root.left, low, high)
+    else -> root.also {
+        it.left = trimBST(it.left, low, high)
+        it.right = trimBST(it.right, low, high)
+    }
 }
 
diff --git a/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeProdVariant.kt b/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeProdVariant.kt
index 9f6d86e..e9fff2e 100644
--- a/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeProdVariant.kt
+++ b/contest/src/main/java/com/github/contest/binaryTree/BinaryTreeProdVariant.kt
@@ -118,3 +118,26 @@ fun findDuplicateSubtreesProdVariant(root: TreeNode?): List<TreeNode?> {
         }
 
 }
+
+/**
+ * 606. Construct String from Binary Tree
+ * Prod Variant
+ */
+
+fun tree2strProdVariant(root: TreeNode?): String = when {
+    root == null -> "()"
+    else -> buildString {
+        append(root.`val`)
+        root.left?.let {
+            append("(")
+            append(tree2strProdVariant(it))
+            append(")")
+        }
+        root.right?.let {
+            if (root.left == null) append("()")
+            append("(")
+            append(tree2strProdVariant(it))
+            append(")")
+        }
+    }
+}