1. Introduction to Computational Thinking
Algorithms:
Discussion
(C) Dennis Kafura 2016

2. Algorithms Basic building blocks of an algorithm Questions
action : changing something
sequence : doing one step after another
decision : choosing whether to take an action
iteration : repeating steps until a goal is reached
state : the value of all of the properties
Questions
What can we learn by studying different solutions?
What happens while an algorithm is running?
(C) Dennis Kafura 2016

3. Three solutions
(1)
(2)
(3)
(C) Dennis Kafura 2016

4. What happens when an algorithm is running?
Abstraction of the avatar
Location (where it is in the maze)
Heading (which way it is facing)
North
Abstraction
Properties of the Avatar 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
West
East
Location
Heading
South
Value of each property
(C) Dennis Kafura 2016

5. During execution -1
Location
Heading
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6. During execution -2
Location
Heading
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7. During execution -3
Location
Heading
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8. During execution -4
Location
Heading
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9. State
Idea
State: the value of all properties at a give point in the execution of the algorithm
The state changes as the algorithm is executed (performed)
Only one state exists; previous states forgotten
Note: some states not shown
Location
Heading 1
East
Location
Heading 2
East …
Location
Heading 6
South …
Location
Heading 8
North
(C) Dennis Kafura 2016

10. Nature of state
(dynamic)
(static)
(C) Dennis Kafura 2016