Basics of Computer Science
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This document discusses several concepts in computer science that the author learned on the job after earning their CS degree. It covers how data is represented and stored in Swift using value types like tuples and reference types like classes. It also discusses data structures and how to represent collections of data, highlighting the benefits of immutable, purely functional data structures. The document concludes by discussing singletons and shared state as well as some best practices like avoiding coupling.
![How$many$shared$instances$do$you$see$here?
private var fibRow = [0, 1, 2]
public func fibM(number:Int)->Int{
if number >= fibRow.count {
fibRow.append(fibM(number-2)+fibM(number-1))
}
return fibRow[number]
}
Things'I'learned'on'the'job,'a3er'my'CS'degree](https://image.slidesharecdn.com/basicsofcs-150922084432-lva1-app6892/85/Basics-of-Computer-Science-42-320.jpg)
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Basics of Computer Science
- 11. typealias TPerson = (name:String, age:Int, male:Bool) +-----------------------------------------+--------------------------------------------------+ struct SPerson{ | class CPerson{ let name : String | let name : String let age : Int | let age : Int let male : Bool | let male : Bool } | | init(name : String, age : Int, male : Bool){ +-----------------------------------------+ self.name = name enum EPerson { | self.age = age case Male(name: String, age : Int) | self.male = male case Female(name : String, age : Int) | } | } func name()->String{ | switch self { | case let Male(name, _): | return name | case let Female(name, _): | return name | } | } | } + Things'I'learned'on'the'job,'a3er'my'CS'degree
- 12. Benchmark*in*ms • 000.00786781311035156*Tuple*10M • 000.00405311584472656*Enum*10M • 000.003814697265625*Struct*10M • 813.668251037598*Class*10M Things'I'learned'on'the'job,'a3er'my'CS'degree
- 16. Performance*Characteris0cs • Add$(Prepand$/$Append$/$Insert) • Get$(First$/$Last$/$ByIndex$/$ByValue) • Find$(Biggest$/$Smallest)$ • Delete$(ByIndex$/$ByValue) • Concatenate Things'I'learned'on'the'job,'a3er'my'CS'degree
- 19. +-----------------------------------+-------------------------------------------------------------+ | private protocol List{ | public struct ListNode<T> : List { var tail : List {get} | public let value : T } | private let _tail : List +-----------------------------------+ private var tail : List { | return _tail private struct EmptyList : List{ | } var tail : List { | return EmptyList() | private init(value: T, tail : List){ } | self.value = value } | self._tail = tail | } | | public subscript(var index : UInt) -> ListNode<T>?{ +-----------------------------------+ var result : List = self | while(index>0){ | result = result.tail | index-- infix operator => { | } associativity right | return result as? ListNode<T> precedence 150 | } } | | } +-----------------------------------+-------------------------------------------------------------+ public func => <T>(lhs: T, rhs: ListNode<T>?) -> ListNode<T> { if let node = rhs { return ListNode(value: lhs, tail: node) } return ListNode(value: lhs, tail: EmptyList()) } Things'I'learned'on'the'job,'a3er'my'CS'degree
- 20. Benchmark*in*ms • 208.853006362915+List+1K • 000.30207633972168+BoxEList+1K • 000.0660419464111328+ClassList+1K • 000.0400543212890625+EEList+1K • 000.0429153442382812+Array+1K Things'I'learned'on'the'job,'a3er'my'CS'degree
- 35. Benchmark*in*ms • 208.853006362915+List+1K • 000.30207633972168+BoxEList+1K • 000.0660419464111328+ClassList+1K • 000.0400543212890625+EEList+1K • 000.0429153442382812+Array+1K Things'I'learned'on'the'job,'a3er'my'CS'degree
- 36. enum EEList<Element> { case End indirect case Node(Element, next: EEList<Element>) var value: Element? { switch self { case let Node(x, _): return x case End: return nil } } } extension EEList { func cons(x: Element) -> EEList { return .Node(x, next: self) } } Things'I'learned'on'the'job,'a3er'my'CS'degree
- 42. How$many$shared$instances$do$you$see$here? private var fibRow = [0, 1, 2] public func fibM(number:Int)->Int{ if number >= fibRow.count { fibRow.append(fibM(number-2)+fibM(number-1)) } return fibRow[number] } Things'I'learned'on'the'job,'a3er'my'CS'degree
- 47. +----------------+ +----------------+ | | | | | SomethingA +-------> | AbstractB | | | | | +----------------+ +-------+--------+ ^ | | | +-------+--------+ | | | SomethingB | | | +----------------+ Things'I'learned'on'the'job,'a3er'my'CS'degree
- 49. Shared'resources: • Memory • I/O • Network Things'I'learned'on'the'job,'a3er'my'CS'degree
- 52. Apple%takes%cares%of%it: • default... • shared... • main... Things'I'learned'on'the'job,'a3er'my'CS'degree
- 57. Links: • PerformanceTest • Fibonacci • Fork2Join2illustra6on • Linked2List2implementa6on2with2Swi=22Enum • Pure2Func6onal2Data2Structures Things'I'learned'on'the'job,'a3er'my'CS'degree