Merge pull request #1184 from Ykhan799/main

Create: 543-Diameter-of-Binary-Tree.cs, 235-Lowest-Common-Ancestor-of-a-Binary-Search-Tree.cs

Author: Ykhan799

Diff for: csharp/235-Lowest-Common-Ancestor-of-a-Binary-Search-Tree.cs

@@ -0,0 +1,25 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int x) { val = x; }
+ * }
+ */
+
+public class Solution {
+    public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+        // Traverse Right child
+        if (p.val > root.val && q.val > root.val) {
+            return LowestCommonAncestor(root.right, p, q);
+        }
+        
+        // Traverse Left Child
+        if (p.val < root.val && q.val < root.val) {
+            return LowestCommonAncestor(root.left, p, q);
+        }
+        
+        return root;
+    }
+}

Diff for: csharp/543-Diameter-of-Binary-Tree.cs

@@ -0,0 +1,31 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+public class Solution {
+    int result = -1;
+    
+    public int DiameterOfBinaryTree(TreeNode root) {
+        dfs(root);
+        return result;
+    }
+    
+    private int dfs(TreeNode current) {
+        if (current == null) {
+            return -1;
+        }
+        int left = 1 + dfs(current.left);
+        int right = 1 + dfs(current.right);
+        result = Math.Max(result, (left + right));
+        return Math.Max(left, right);
+    }
+}