Tree Traversal DFS

Height + Depth DFS

Comparison + Validation

Path-Based DFS

Global State + DFS

Tree Construction

Level Order BFS

BST-Specific Patterns

Tree + Graph Conversion

Iterative DFS

patterns:

• DFS (postorder) → compute from children
• DFS (preorder) → pass state downward
• BFS → process levels
• Stack → simulate recursion
• Queue → simulate levels

use DFS when:

• Bottom-up computation (height, diameter)
• Path exploration
• Validation (BST, symmetry)

use BST properties when:

• Sorted order matters
• Searching efficiently

use BFS when:

• Level-based output
• Shortest path in tree
• “View” problems (right/left view)