1. Computer programming
IV. Algorithms

2. Recap: What is computer programming?
Telling computers to solve a problem
Solve problem and come up with solution (algorithm)
Break down the problem into step by step solution
Write the solution in a programming language (coding)

3. Computer Programming repetition
Algorithm for going to school in the morning
sequencing
conditional
logic

4. Algorithms:
Decision tree
Pattern recognition
Divide and conquer

5. Algorithm: Decision Trees (Harry Potter's sorting hat)
Person
Hair Length
Teacher?
Brave things
Likes Muggles?
Medieval wizards?
House
Harry
short no 20
yes
Gryffindor
Draco
long 4
Slytherin
Ron 15
Snape 16
Hermione 25
Pansy 17
McGonagall
Ginny 18
Millicent 6
Merlin 50
Blaise 8
???
Salazar 30

6. Algorithm: Decision Trees? ?
>= 15 brave things
< 15 brave things
Train: 7 of 10 correct (70% correct)
Slytherin
Test: 1 of 2 correct
(50% correct)
Gryffindor

7. Algorithm: Decision Trees? ?
Likes Muggles
Doesn’t like Muggles
Non Medieval
Wizards
Medieval Wizards
Slytherin
Test: 2 of 2 correct (100% correct)
Gryffindor
Slytherin

8. Algorithm: Decision Trees
Guess a number between 0 and 3:
X > 1?
X > 0?
X > 2?
X = 0
X = 1
X = 2
X = 3 no
yes

9. Coding: Decision Trees
Guess a number between 0 and 3:
If X > 1 then:
If X > 2 then:
X = 3
Else:
X = 2
If X > 0 then:
X = 1
X = 0
X > 1?
X > 0?
X > 2?
X = 0
X = 1
X = 2
X = 3 no
yes

10. Algorithm: Pattern Recognition
Rock-Paper-Scissors: Human VS Computer
The computer guesses
what we are going to do
next based on the patterns of
our previous throws

11. Algorithm: Pattern Recognition
bakaji bavwa bamona bana
The women saw the children

12. Algorithm: Pattern Recognition
The child: muana
The children: bana
The woman: mukaji
The women: bakaji
The man: muluma
The men: baluma
The lion: ntambwe
The lions: bantambwe
The small lions: tubantambwe
The small lion: kantambwe
Saw: mumona/bamona/tumona/kamona

13. Algorithm: Sorting We sort things all the time! Packing, moving, ...
How can we teach computers how to sort things?

14. Algorithm: Selection sort
While there is still some heights to be sorted:
Select the shortest from the set and put it to one side 45

15. Algorithm: Divide &Conquer Quick Sort
While the group has more than 1 object
Pick one object at random, put objects shorter than it on its left and objects taller than it on its right
Repeat this same procedure on the left and right groups

16. Algorithm: Quick Sort 9

17. Algorithm: Quick Sort 9

18. Algorithm: Quick Sort 16

19. Algorithm: Quick Sort 16

20. Algorithm: Quick Sort 19

21. Algorithm: Quick Sort 19

22. Algorithm: Quick Sort 19

23. Algorithm: Quick Sort 19 While the group has more than 1 object
Pick one object at random, put objects shorter than it on its left and objects taller than it on its right
Repeat this same procedure on the left and right groups 19

24. Coding: Choose Your Own Adventure
Use scratch.mit.edu
Create backdrops
Create scenes
Match scenes to backdrops
Code the choices

25. Coding: Robot Singing
Use

26. Algorithm: Divide & Conquer Tower of Hanoi
Think how we can use divide and conquer to solve the problem:
Tower of Hanoi (
Next week:
Building your own website!

27. Questions?