problem: 0572 subtree of another tree

0572 Subtree of Another Tree/0572 Subtree of Another Tree.md

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+# 0572. Subtree of Another Tree
+
+* Difficulty: easy
+* Link: https://leetcode.com/problems/subtree-of-another-tree/
+* Topics: DFS-BFS
+
+# Clarification
+
+1. Check the inputs and outputs
+
+# Solution (BFS)
+
+### Thought Process
+
+- traverse the root tree first
+- compare the current node with subtree (isSame?)
+- Implement
+
+    ```python
+    # 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 isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
+
+            def isSame(node1: Optional[TreeNode], node2: Optional[TreeNode]) -> bool:
+                if not node1 and not node2:
+                    return True
+                if not node1 or not node2:
+                    return False
+                if node1.val != node2.val:
+                    return False
+                return isSame(node1.left, node2.left) and isSame(node1.right, node2.right)
+
+            # BFS
+            q = collections.deque()
+            q.append(root)
+            while q:
+                current = q.pop()
+                if isSame(current, subRoot):
+                    return True
+                if current:
+                    q.append(current.left)
+                    q.append(current.right)
+
+            return False
+    ```
+
+
+### Complexity
+
+- Time complexity: O(V)
+    - 遍歷兩棵樹的節點
+- Space complexity: