- Invert Binary Tree #226

Author: ayosecu

invert-binary-tree/ayosecu.py

@@ -0,0 +1,72 @@
+from typing import Optional
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+class Solution:
+    """
+        - Time Complexity: O(N), N = The number of nodes
+        - Space complexity: O(H), H = The height of the tree
+    """
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+        if not root:
+            return
+        
+        root.left, root.right = root.right, root.left
+
+        self.invertTree(root.left)
+        self.invertTree(root.right)
+
+        return root
+
+def build_tree(values):
+    from collections import deque
+    if not values:
+        return None
+    root = TreeNode(values[0])
+    queue = deque([root])
+    i = 1
+    while i < len(values):
+        node = queue.popleft()
+        if values[i] is not None:
+            node.left = TreeNode(values[i])
+            queue.append(node.left)
+        i += 1
+        if i < len(values) and values[i] is not None:
+            node.right = TreeNode(values[i])
+            queue.append(node.right)
+        i += 1
+    return root
+
+def tree_to_list(root):
+    from collections import deque
+    if not root:
+        return []
+    result = []
+    queue = deque([root])
+    while queue:
+        node = queue.popleft()
+        if node:
+            result.append(node.val)
+            queue.append(node.left)
+            queue.append(node.right)
+        else:
+            result.append(None)
+    # Remove trailing None
+    while result and result[-1] is None:
+        result.pop()
+    return result
+
+tc = [
+        ([4,2,7,1,3,6,9], [4,7,2,9,6,3,1]),
+        ([2,1,3], [2,3,1]),
+        ([], [])
+]
+
+sol = Solution()
+for i, (n, e) in enumerate(tc, 1):
+    r = tree_to_list(sol.invertTree(build_tree(n)))
+    print(f"TC {i} is Passed!" if r == e else f"TC {i} is Failed! - Expected: {e}, Result: {r}")