Loop

Trees

Recursion on binary trees, BFS by level, BST ordering, and the bubble-up answer pattern.

0 of 8 lessons complete · 181 min total

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  1. Trees: Recursion That Bubbles UpDFS traversal orders, the return-a-value-while-tracking-a-global pattern (diameter, path sum), and passing state down (bounds, path max).Lesson · 17 minNot completed
  2. DFS with a Visible Call StackMaking recursion physical.Animation · 10 minNot completed
  3. Level-Order BFSQueue-driven traversal one level at a time.Animation · 10 minNot completed
  4. The BST Ordering PropertyWhy left < node < right enables O(log n) descent, inorder-gives-sorted, validation with min/max bounds, and LCA by direction.Lesson · 14 minNot completed
  5. Practice: Recursive FoundationsThe six canonical easy DFS problems — each one a variation of return-height-while-checking.easy×66 problems · 0 solvedPractice · 36 minNot completed
  6. Practice: Levels & BST RulesBFS by level, carrying state down the tree, and exploiting BST ordering.medium×55 problems · 0 solvedPractice · 40 minNot completed
  7. Practice: Construction & Hard PathsIterative inorder, building from traversals, max path gain, and serialization with null markers.medium×2hard×24 problems · 0 solvedPractice · 45 minNot completed
  8. Trees CheckpointTraversal orders, BST invariants, global-vs-returned values, and BFS/DFS selection.Checkpoint · 9 minNot completed