Update 0968.监控二叉树.md

Added python version code

problems/0968.监控二叉树.md

@@ -346,8 +346,27 @@ class Solution {
 
 
 Python：
-
+```python
-
+class Solution:
+    def minCameraCover(self, root: TreeNode) -> int:
+        result = 0
+        def traversal(cur):
+            nonlocal result
+            if not cur:
+                return 2
+            left = traversal(cur.left)
+            right = traversal(cur.right)
+            if left == 2 and right == 2:
+                return 0
+            elif left == 0 or right == 0:
+                result += 1
+                return 1
+            elif left == 1 or right == 1:
+                return 2
+            else: return -1
+        if traversal(root) == 0: result += 1
+        return result
+```
 Go：