Computer Science: The Good Parts

Kansas City Developers Conference

Transcript

1. Computer Science: The Good Parts csthegoodparts.com @jeffcohen
4. 1. Encoding All The Things 2. Containers for Things 3. Doing Things 4. Building Big Things 5. Thinking About Things
5. Data Structures
6. Data Structures
7. Linked List 60 31 5 45 70 head
8. Queue New elements are appended to the end of the list 60 31 5 45 70 head
9. Stack 60 45 70 31 5 head New elements are inserted at the front of the list
10. 60 31 5 45 80 70 74 99 87 68 Binary
 Tree root
11. Graph
15. Algorithms
16. Babbage and Lovelace
17. Apollo 11
18. Margaret Hamilton Source code of the Apollo Guidance Computer
19. Complexity
20. Complexity Some computer programming implementations are more complex than others.
21. Complexity A "green" test suite is not an indicator of sustainability nor is it a guarantee of an optimal solution.
22. Complexity Science relies on standard systems of weights and measures. For software, we measure resources, which are typically time and space.
23. O(n) def search(name_to_find, names) for name in names if name == name_to_find return true end end return false end
24. def search(name_to_find, names) for name in names if name == name_to_find return true end end return false end O(n) 0 100 200 300 O(n)
25. O(log n) def search(name_to_find, sorted_names) 
 return false if sorted_names.size == 0 
 midpoint = sorted_names.length / 2 
 
 if name < sorted_names[midpoint].name 
 search(name_to_find, sorted_names[0, midpoint]) 
 elsif name > sorted_names[midpoint].name
 search(name_to_find, sorted_names[midpoint, -1]) end return true
 end
26. def search(name_to_find, sorted_names) 
 return false if sorted_names.size == 0 
 midpoint = sorted_names.length / 2 
 
 if name < sorted_names[midpoint].name 
 search(name_to_find, sorted_names[0, midpoint]) 
 elsif name > sorted_names[midpoint].name
 search(name_to_find, sorted_names[midpoint, -1]) end return true
 end O(log n) 0 100 200 300 O(log n) O(n)
27. Atom.io blog post
28. O(n2) def all_permuations(items) items.map do |item| items.map { |inner_item| [item, inner_item] } end end [1,2,3] => [[1,1], [1,2], [1,3], [2, 1], [2, 2], [2, 3], [3, 1], [3, 2], [3, 3]]
29. def all_permuations(items) items.map do |item| items.map { |inner_item| [item, inner_item] } end end O(n2) 0 100 200 300 O(n2) O(n) O(log n)
30. Cryptography
31. Cryptography
32. Cryptography
33. Cryptography
34. The Future
35. Traditions We know our history. We value progress over reinvention. We seek solutions to meaningful problems.
36. Alan Turing
37. Alan Turing Computer science
 is not
 computer programming
38. Alan Turing It's a way of thinking
39. Grace Hopper
40. Grace Hopper
41. Grace Hopper Humans are allergic to change. They love to say, "We've always done it this way." I try to fight that.
 
 That's why I have a clock on my wall that runs counter-clockwise.
42. Grace Hopper A ship in port is safe; but that is not what ships are built for. Sail out to sea and do new things.
43. Questions? Thoughts? Find me on twitter @jeffcohen Notes, Links, Resources: csthegoodparts.com