Algorithm Learning/Preorder Traversal

Preorder Traversal

Binary tree traversal that visits the root first.

EasyTreeRecursionTraversal

Definition

Preorder traversal visits nodes in Root -> Left subtree -> Right subtree order.

Key Characteristics

  • Visit root first
  • Recursively traverse left then right subtree
  • A form of DFS (Depth-First Search)

Use Cases

Used in these scenarios:

📋

Tree Copy

Useful for copying tree structure as root is visited first

🧮

Expression Tree Prefix

Generate prefix notation with operator first

📁

File System Traversal

Explore directory structure top-down

Complexity

Time Complexity

Best
O(N)
Average
O(N)
Worst
O(N)

Space Complexity

O(H)

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