Time: 3 ms (81.43%), Space: 18.4 MB (99.35%) - LeetHub

Author: hogan-tech

0549-binary-tree-longest-consecutive-sequence-ii/0549-binary-tree-longest-consecutive-sequence-ii.py

@@ -0,0 +1,50 @@
+# time complexity: O(n)
+# space complexity: O(n)
+from typing import List, 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:
+        def longestPath(root: TreeNode) -> List[int]:
+            nonlocal maxval
+
+            if not root:
+                return [0, 0]
+
+            increase = decrease = 1
+            if root.left:
+                left = longestPath(root.left)
+                if (root.val == root.left.val + 1):
+                    decrease = left[1] + 1
+                elif (root.val == root.left.val - 1):
+                    increase = left[0] + 1
+
+            if root.right:
+                right = longestPath(root.right)
+                if (root.val == root.right.val + 1):
+                    decrease = max(decrease, right[1] + 1)
+                elif (root.val == root.right.val - 1):
+                    increase = max(increase, right[0] + 1)
+
+            maxval = max(maxval, decrease + increase - 1)
+            return [increase, decrease]
+
+        maxval = 0
+        longestPath(root)
+        return maxval
+
+
+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))