# week 11 Workshop 8 Hierarchical Data Structures Part 2 – Application: Expression Trees

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Question

What is parsing?
Arithmetic expressions are converted into an (equivalent) unique form. Compliers must generate unambiguous code in which one operation is executed at a time.

what is infix notation?
the placement of operators between operands—"infixed operators"—such as the plus sign in 2 + 2.

what is postfix notation?
arithmetic expressions in which the operands appear before their operators. This notation is used in Complier design to generate our unambiguous code eg 2 2 +

what is prefix notation?
+ 2 2

what are the two methods to convert from infix to post fix notation
Using Dijkstra’s Algorithm or Drawing an Expression Tree / Parse Tree

what is an Expression Tree / Parse Tree?
Write the expression out as a BST then navigate it using pre or post order traversal to achive the corrected output

what is Dijkstra’s Algorithm?
Work through infix expression from left to right Operands are output immediately. Operators are stored in a stack until required

what are the precedences for dijkstras algorithm?
Open bracket (0 - lowest Addition and Subtraction 1 Multiplication and Division 2 Raise to the power 3 – highest