import Foundation
print("Hello, World!")
//protocol IteratorProtocol {
// associatedtype Element
// mutating func next() -> Element?
//}
struct Ones: IteratorProtocol {
typealias Element = Int
mutating func next() -> Int? {
return 1
}
}
var ones = Ones()
print(ones.next())
print(ones.next())
//struct Fibonacci: IteratorProtocol {
// typealias Element = Int
//
// private var state = (0, 1)
//
// mutating func next() -> Int? {
// let nextNumber = state.0
// state = (state.1, state.0 + state.1)
// return nextNumber
// }
//
//}
//var fibonacci = Fibonacci()
//print(fibonacci.next())
//print(fibonacci.next())
//print(fibonacci.next())
//print(fibonacci.next())
//print(fibonacci.next())
//print(fibonacci.next())
//
//var fibonacci1 = fibonacci
//print(fibonacci1.next())
//protocol Sequence {
// associatedtype Element
// associatedtype Iterator: IteratorProtocol where Iterator.Element == Element
//
// func makeIterator() -> Iterator
//}
struct FiboIter: IteratorProtocol {
typealias Element = Int
var state = (0, 1)
mutating func next() -> Int? {
let nextNumber = state.0
self.state = (state.1, state.0 + state.1)
return nextNumber
}
}
struct Fibonacci: Sequence {
typealias Element = Int
func makeIterator() -> FiboIter {
return FiboIter()
}
}
var fibs = Fibonacci()
var fib1 = fibs.makeIterator()
print(fib1.next())
print(fib1.next())
print(fib1.next())
print(fib1.next())
print(fib1.next())
print(fib1.next())
print(fib1.next())
for n in Fibonacci() {
if n <= 5 {
print(n)
} else {
break
}
}
var arrayInt: [Int] = []
var sumInt = arrayInt.reduce(0, +)
print(sumInt)
var arrStr: [String] = []
var sumStr = arrStr.reduce("", +)
print(sumStr)
func reduce1(of sequence: S, _ partical: (E, E) -> E) -> E?
where S: Sequence, E == S.Element {
var iter: S.Iterator = sequence.makeIterator()
guard var accumulated = iter.next() else {
return nil
}
while let element = iter.next() {
accumulated = partical(accumulated, element)
}
return accumulated
}
extension Sequence {
//FixedWidthInteger, SignedInteger , 先就这么着吧,:slightly_smiling:
func reduceFromZero(of sequence: S, _ partical: (E, E) -> E) -> E where S: Sequence, E: FixedWidthInteger, E: SignedInteger, E == S.Element {
var iter = sequence.makeIterator()
guard var accumulated = iter.next() else { return 0 }
while let element = iter.next() {
accumulated = partical(accumulated, element)
}
return accumulated
}
}
print(reduce1(of: arrayInt, +))
print([1].elementsEqual([1]))
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