some changes

BST/36_Minimum_Element_In_BST.py

@@ -0,0 +1,21 @@
+# Problem: Minimum_Element_In_BST
+# URL: https://practice.geeksforgeeks.org/problems/minimum-element-in-bst/1
+
+#User function Template for python3
+
+"""
+class Node:
+    def __init__(self, val):
+        self.right = None
+        self.data = val
+        self.left = None
+"""
+
+class Solution:
+    #Function to find the minimum element in the given BST.
+    def minValue(self, root):
+        ##Your code here
+        if (root.left==None):
+            return root.data
+        return self.minValue(root.left)
+

BST/Easy/01_Ceil_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/ceil-in-a-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 01_Ceil_in_BST.py
+    pass

BST/Easy/02_Floor_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/floor-in-a-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 02_Floor_in_BST.py
+    pass

BST/Easy/03_Insert_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/insert-into-a-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 03_Insert_in_BST.py
+    pass

BST/Easy/04_Introduction_to_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/introduction-to-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 04_Introduction_to_BST.py
+    pass

BST/Easy/05_Search_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/search-in-a-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 05_Search_in_BST.py
+    pass

BST/Easy/06_Search_and_Insertion.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/binary-search-tree-set-1-search-and-insertion/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 06_Search_and_Insertion.py
+    pass

BST/Hard/01_Merge_2_BSTs.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/merge-two-binary-search-trees
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 01_Merge_2_BSTs.py
+    pass

BST/Hard/02_Recover_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/recover-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 02_Recover_BST.py
+    pass

BST/Hard/03_Largest_BST_in_Binary_Tree.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/largest-bst/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 03_Largest_BST_in_Binary_Tree.py
+    pass

BST/Hard/04_Convert_Normal_BST_to_Balanced_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/convert-normal-bst-balanced-bst/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 04_Convert_Normal_BST_to_Balanced_BST.py
+    pass

BST/Hard/05_Flatten_BST_to_Sorted_List.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/flatten-bst-to-sorted-list-increasing-order/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 05_Flatten_BST_to_Sorted_List.py
+    pass

BST/Hard/06_Merge_Two_Balanced_BSTs.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/merge-two-balanced-binary-search-trees/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 06_Merge_Two_Balanced_BSTs.py
+    pass

BST/Medium/01_Delete_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/delete-node-in-a-binary-search-tree
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 01_Delete_in_BST.py
+    pass

BST/Medium/02_Find_Kth_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/kth-smallest-element-in-a-bst
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 02_Find_Kth_in_BST.py
+    pass

BST/Medium/03_Check_BST_or_BT.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/check-for-bst/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 03_Check_BST_or_BT.py
+    pass

BST/Medium/04_LCA_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/lowest-common-ancestor-in-a-bst/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 04_LCA_in_BST.py
+    pass

BST/Medium/05_Construct_BST_from_Preorder.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/construct-bst-from-given-preorder-traversa/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 05_Construct_BST_from_Preorder.py
+    pass

BST/Medium/06_Inorder_Successor_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/predecessor-and-successor/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 06_Inorder_Successor_in_BST.py
+    pass

BST/Medium/07_Two_Sum_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://leetcode.com/problems/two-sum-iv-input-is-a-bst
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 07_Two_Sum_in_BST.py
+    pass

BST/Medium/08_Find_Min_Max_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/minimum-element-in-bst/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 08_Find_Min_Max_in_BST.py
+    pass

BST/Medium/09_Binary_Tree_to_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/binary-tree-to-bst/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 09_Binary_Tree_to_BST.py
+    pass

BST/Medium/10_Count_BST_Nodes_in_Range.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/count-bst-nodes-that-lie-in-a-given-range/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 10_Count_BST_Nodes_in_Range.py
+    pass

BST/Medium/11_Brothers_from_Different_Root.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/brothers-from-different-root/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 11_Brothers_from_Different_Root.py
+    pass

BST/Medium/12_Find_Median_in_BST.py

@@ -0,0 +1,6 @@
+# Problem URL: https://www.geeksforgeeks.org/find-median-bst-time-o1-space/
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 12_Find_Median_in_BST.py
+    pass

BST/Medium/13_Check_Whether_BST_Contains_Dead_End.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/check-whether-bst-contains-dead-end/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 13_Check_Whether_BST_Contains_Dead_End.py
+    pass

BST/Medium/14_Preorder_to_Postorder.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/preorder-to-postorder/0
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 14_Preorder_to_Postorder.py
+    pass

BST/Medium/15_Populate_Inorder_Successor.py

@@ -0,0 +1,6 @@
+# Problem URL: https://practice.geeksforgeeks.org/problems/populate-inorder-successor-for-all-nodes/1
+# TODO: Implement the solution
+
+def solution():
+    # TODO: Implement the solution for 15_Populate_Inorder_Successor.py
+    pass

BST/file.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# List of problems with category, filename, and URL
+problems=(
+  # Easy
+  "Easy 01_Ceil_in_BST.py https://leetcode.com/problems/ceil-in-a-binary-search-tree"
+  "Easy 02_Floor_in_BST.py https://leetcode.com/problems/floor-in-a-binary-search-tree"
+  "Easy 03_Insert_in_BST.py https://leetcode.com/problems/insert-into-a-binary-search-tree"
+  "Easy 04_Introduction_to_BST.py https://leetcode.com/problems/introduction-to-binary-search-tree"
+  "Easy 05_Search_in_BST.py https://leetcode.com/problems/search-in-a-binary-search-tree"
+  "Easy 06_Search_and_Insertion.py https://www.geeksforgeeks.org/binary-search-tree-set-1-search-and-insertion/"
+
+  # Medium
+  "Medium 01_Delete_in_BST.py https://leetcode.com/problems/delete-node-in-a-binary-search-tree"
+  "Medium 02_Find_Kth_in_BST.py https://leetcode.com/problems/kth-smallest-element-in-a-bst"
+  "Medium 03_Check_BST_or_BT.py https://practice.geeksforgeeks.org/problems/check-for-bst/1"
+  "Medium 04_LCA_in_BST.py https://practice.geeksforgeeks.org/problems/lowest-common-ancestor-in-a-bst/1"
+  "Medium 05_Construct_BST_from_Preorder.py https://www.geeksforgeeks.org/construct-bst-from-given-preorder-traversa/"
+  "Medium 06_Inorder_Successor_in_BST.py https://practice.geeksforgeeks.org/problems/predecessor-and-successor/1"
+  "Medium 07_Two_Sum_in_BST.py https://leetcode.com/problems/two-sum-iv-input-is-a-bst"
+  "Medium 08_Find_Min_Max_in_BST.py https://practice.geeksforgeeks.org/problems/minimum-element-in-bst/1"
+  "Medium 09_Binary_Tree_to_BST.py https://practice.geeksforgeeks.org/problems/binary-tree-to-bst/1"
+  "Medium 10_Count_BST_Nodes_in_Range.py https://practice.geeksforgeeks.org/problems/count-bst-nodes-that-lie-in-a-given-range/1"
+  "Medium 11_Brothers_from_Different_Root.py https://practice.geeksforgeeks.org/problems/brothers-from-different-root/1"
+  "Medium 12_Find_Median_in_BST.py https://www.geeksforgeeks.org/find-median-bst-time-o1-space/"
+  "Medium 13_Check_Whether_BST_Contains_Dead_End.py https://practice.geeksforgeeks.org/problems/check-whether-bst-contains-dead-end/1"
+  "Medium 14_Preorder_to_Postorder.py https://practice.geeksforgeeks.org/problems/preorder-to-postorder/0"
+  "Medium 15_Populate_Inorder_Successor.py https://practice.geeksforgeeks.org/problems/populate-inorder-successor-for-all-nodes/1"
+
+  # Hard
+  "Hard 01_Merge_2_BSTs.py https://leetcode.com/problems/merge-two-binary-search-trees"
+  "Hard 02_Recover_BST.py https://leetcode.com/problems/recover-binary-search-tree"
+  "Hard 03_Largest_BST_in_Binary_Tree.py https://www.geeksforgeeks.org/largest-bst/"
+  "Hard 04_Convert_Normal_BST_to_Balanced_BST.py https://www.geeksforgeeks.org/convert-normal-bst-balanced-bst/"
+  "Hard 05_Flatten_BST_to_Sorted_List.py https://www.geeksforgeeks.org/flatten-bst-to-sorted-list-increasing-order/"
+  "Hard 06_Merge_Two_Balanced_BSTs.py https://www.geeksforgeeks.org/merge-two-balanced-binary-search-trees/"
+)
+
+# Create directories
+mkdir -p Easy Medium Hard
+
+# Create .py files
+for problem in "${problems[@]}"; do
+  IFS=' ' read -r category filename url <<< "$problem"
+  filepath="$category/$filename"
+
+  # Check if the file already exists
+  if [[ ! -f "$filepath" ]]; then
+    echo "# Problem URL: $url" > "$filepath"
+    echo "# TODO: Implement the solution" >> "$filepath"
+    echo >> "$filepath"
+    echo "def solution():" >> "$filepath"
+    echo "    # TODO: Implement the solution for $filename" >> "$filepath"
+    echo "    pass" >> "$filepath"
+
+    echo "Created $filepath"
+  else
+    echo "$filepath already exists, skipping."
+  fi
+done

Tree/Hard/87_Validate_Binary_Search_Tree.py

@@ -1,6 +1,24 @@
 # Problem: Validate_Binary_Search_Tree
 # URL: https://leetcode.com/problems/validate-binary-search-tree/description/
 
-def solution():
-    # TODO: Implement the solution for Validate_Binary_Search_Tree
-    pass
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def isValidBST(self, root: Optional[TreeNode]) -> bool:
+        def is_valid(node, lower=float('-inf'), upper=float('inf')):
+            if not node:
+                return True
+            val = node.val
+            if val <= lower or val >= upper:
+                return False
+            if not is_valid(node.right, val, upper):
+                return False
+            if not is_valid(node.left, lower, val):
+                return False
+            return True
+
+        return is_valid(root)