Sing, Pray

Announcements
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* The last day to take the test was yesterday.
* Average time taking the test was 1h46m

Clarifications
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Test typo on the Stack problem.  The last number pushed onto S1 was 8 (not 7).
	
Outline
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Review Lists
Doubly-Linked Lists
Discuss Trees



In a preorder traversal, work at a node is performed before its children are processed.  The traversal takes constant time per node.

In a postorder traversal, work at a node is performed after its children are evaluated.  The traversal takes constant time per node.