1. Welcome back to Software Development!
Return graded assignments
Review classroom procedures:
Start of class procedure
Reminders:
Missing assignments
Friday quiz – open book

2. Basic Flowchart Symbols
Start or end of algorithm:
Action/process step:
Input or output operation:
Decision:
Leave the house
At school - done
Start the car
Ask for directions
Is the stoplight red?
Yes No

3. Largest Number Algorithm
Take the 1st number – at the start, it is the largest we’ve seen Do
Get the next number from the list
Compare the current largest to the next number
If the next number is larger
Then take it as the largest
Until there are no more numbers left
The number you are left with is the largest

5. Get 1st # as largest Get nxt # Compare nxt to largest Nxt # larger?
Yes
Nxt is new
largest No
Flowchart for my algo
Emphasize
Loop is obvious
Decisions are obvious
Loop termination condition…end of list
General…works for any list of numbers
Only specific is starting in the list (1st item in list)
More #’s ?
Yes No
Done!

6. Task: find the largest number in a list of integers

7. Task: find the largest number in a list of integers
Possible Algorithm:

8. Task: find the largest number in a list of integers
Possible Algorithm:
Get the list

9. Task: find the largest number in a list of integers
Possible Algorithm:
Get the list
Get the biggest number from the list

10. Task: find the largest number in a list of integers
Possible Algorithm:
Get the list
Get the biggest number from the list
Done

11. Task: find the largest number in a list of integers
Possible Algorithm:
Get the list
Get the biggest number from the list
Done

12. Task: find the largest number in a list of integers
Possible Algorithm:
Get the list
Get the biggest number from the list
Done
All you are doing is restating the problem…

13. Task: find the largest number in a list of integers

14. Task: find the largest number in a list of integers
Algorithm:

15. Task: find the largest number in a list of integers
Algorithm:
Get the list

16. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest

17. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest
Take the largest number

18. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest
Take the largest number
Done

19. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest
Take the largest number
Done

20. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest
Take the largest number
Done

21. Task: find the largest number in a list of integers
Algorithm:
Get the list
Sort the list from smallest to largest
Take the largest number
Done
You’ve actually created a harder problem that includes this one!

22. Algorithm Guidelines…

23. Algorithm Guidelines…
One action per step or flowchart box:

24. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?

25. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.

26. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…

27. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...

28. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...
Likely more than one action in the step.

29. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...
Likely more than one action in the step.
Look for buried questions or decisions

30. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...
Likely more than one action in the step.
Look for buried questions or decisions
Looping words: continue, do, repeat (the flow arrows covers these)

31. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...
Likely more than one action in the step.
Look for buried questions or decisions
Looping words: continue, do, repeat (the flow arrows covers these)
Decision words: is, if, ?

32. Algorithm Guidelines…
One action per step or flowchart box:
Too many words in the step / box?
Keep it short and sweet … 5-6 words per step / box.
Conjunction Junction…
And, or, but, unless, ...
Likely more than one action in the step.
Look for buried questions or decisions
Looping words: continue, do, repeat (the flow arrows covers these)
Decision words: is, if, ?
“Keep the larger number” is a decision (if x > y) and an action (keep x)…2 steps

33. Broken down enough?

34. Broken down enough?
Swap “this” and “that” number in the list

35. Broken down enough? Swap “this” and “that” number in the list
Is this one step?

36. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…

37. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…
1) Get a temporary copy of “this” number

38. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…
1) Get a temporary copy of “this” number
2) Move “that” number to “this” number’s slot

39. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…
1) Get a temporary copy of “this” number
2) Move “that” number to “this” number’s slot
3) Move “this” number to “that” number’s old slot

40. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…
1) Get a temporary copy of “this” number
2) Move “that” number to “this” number’s slot
3) Move “this” number to “that” number’s old slot
If you understand this, you can put “swap A with B” as a flowchart step

41. Broken down enough? Swap “this” and “that” number in the list
Is this one step?
Actually no…
1) Get a temporary copy of “this” number
2) Move “that” number to “this” number’s slot
3) Move “this” number to “that” number’s old slot
If you understand this, you can put “swap A with B” as a flowchart step
When you code it, you will need to actually code the above steps

42. Practice Guided practice Rewrite “largest number” algo
Focus on general solution
Loop termination condition
Flowchart your algo
Team effort
Turn in at end of class…graded.
FINISH ALGO BEFORE STARTING FLOWCHART!
About 30 mins

43. Practice
Review and rewrite your “select the largest number” algorithm for clarity and conciseness.

44. Practice
Review and rewrite your “select the largest number” algorithm for clarity and conciseness.
Flowchart your “select the largest number” algorithm.

45. Practice
Review and rewrite your “select the largest number” algorithm for clarity and conciseness.
Flowchart your “select the largest number” algorithm.
You have 30 minutes…

46. Hmm, an idea… Demonstrate power of a general algo
Simple change solves a different problem
What change needed to find smallest number?
10 minutes, group work

47. Hmm, an idea…
What would you have to do to your “largest number” algorithm to make it a “smallest number” algorithm?

48. Hmm, an idea…
What would you have to do to your “largest number” algorithm to make it a “smallest number” algorithm?
Just change your comparison decision!

49. A Harder Task Extend and reinforce power of general solution.
Use either algos to develop algo to sort a list of numbers
Tool box reminder:
Algos are tools to be used
Keep a “tool box” of your valuable tools
Use the right tool for the job
Rest of class (30 minute goal)
Close with “clear/unclear windows”

50. A Harder Task
See if you can find a way to use your “largest number” or “smallest number” algorithm to sort a (any) list of numbers.

51. A Harder Task
See if you can find a way to use your “largest number” or “smallest number” algorithm to sort a (any) list of numbers.
Work with your partner

52. A Harder Task
See if you can find a way to use your “largest number” or “smallest number” algorithm to sort a (any) list of numbers.
Work with your partner
Names on your work paper

53. A Harder Task
See if you can find a way to use your “largest number” or “smallest number” algorithm to sort a (any) list of numbers.
Work with your partner
Names on your work paper
Turn in at end of class

54. A Harder Task
See if you can find a way to use your “largest number” or “smallest number” algorithm to sort a (any) list of numbers.
Work with your partner
Names on your work paper
Turn in at end of class
You have about 30 minutes…

55. Clear and Unclear Windows
Tomorrow:
Continue sorting algo
Loops exploration