添加（0236.二叉树的最近公共祖先.md）：增加typescript版本

problems/0236.二叉树的最近公共祖先.md

@@ -325,6 +325,20 @@ var lowestCommonAncestor = function(root, p, q) {
 };
 ```
 
+## TypeScript
+
+```typescript
+function lowestCommonAncestor(root: TreeNode | null, p: TreeNode | null, q: TreeNode | null): TreeNode | null {
+    if (root === null || root === p || root === q) return root;
+    const left = lowestCommonAncestor(root.left, p, q);
+    const right = lowestCommonAncestor(root.right, p, q);
+    if (left !== null && right !== null) return root;
+    if (left !== null) return left;
+    if (right !== null) return right;
+    return null;
+};
+```
+
 
 
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