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Author: hogan-tech

0298-binary-tree-longest-consecutive-sequence/0298-binary-tree-longest-consecutive-sequence.py

@@ -0,0 +1,38 @@
+# time complexity: O(n)
+# space complexity: O(n)
+from collections import deque
+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:
+    def longestConsecutive(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        queue = deque([(root, 1)])
+        result = 0
+        while queue:
+            node, count = queue.popleft()
+            result = max(result, count)
+            for nextNode in (node.left, node.right):
+                if nextNode:
+                    if nextNode.val == node.val + 1:
+                        queue.append((nextNode, count + 1))
+                    else:
+                        queue.append((nextNode, 1))
+        return result
+
+
+root = TreeNode(1)
+root.left = TreeNode(2)
+root.left.left = TreeNode(3)
+root.left.right = TreeNode(4)
+root.right = TreeNode(5)
+root.right.right = TreeNode(6)
+print(Solution().longestConsecutive(root))