Update algorithm

README.md

@@ -1,3 +1,3 @@
-# golang-fibonacci-generator
+# golang-fibonacci-generators
 
-Different generator for Fibonacci Numbers written in Golang
+Different generators for Fibonacci Numbers written in Golang. For more information read my corresponding blog entry [Generators in Go](https://blog.haardiek.org/generators-in-go).

channel/fibonacci.go

@@ -1,44 +1,72 @@
-package main
+// package main
 
-import (
-	"fmt"
-)
+// import (
+// 	"fmt"
+// )
 
-type fibonacci struct {
-	Iterator chan *int
-}
+// type fibonacci struct {
+// 	Iterator chan *int
+// }
 
-func (f *fibonacci) Next() *int {
-	return <-f.Iterator
-}
+// func (f *fibonacci) Next() *int {
+// 	return <-f.Iterator
+// }
 
-func newFibonacci(limit int) *fibonacci {
-	f := &fibonacci{
-		make(chan *int, 1),
-	}
+// func newFibonacci(limit int) *fibonacci {
+// 	f := &fibonacci{
+// 		make(chan *int, 1),
+// 	}
+// 	go func() {
+// 		var current, next int
+// 		for {
+// 			if limit == 0 {
+// 				close(f.Iterator)
+// 				return
+// 			}
+// 			if current != 0 || next != 0 {
+// 				next, current = current+next, next
+// 			} else {
+// 				next = 1
+// 			}
+// 			curr := current
+// 			f.Iterator <- &curr
+// 			limit--
+// 		}
+// 	}()
+// 	return f
+// }
+
+// func main() {
+// 	f := newFibonacci(10)
+// 	for r := range f.Iterator {
+// 		fmt.Println(*r)
+// 	}
+// }
+
+package main
+
+import "fmt"
+
+func fibonacci(limit int) chan int {
+	c := make(chan int)
+	a := 0
+	b := 1
 	go func() {
-		var current, next int
 		for {
 			if limit == 0 {
-				close(f.Iterator)
+				close(c)
 				return
 			}
-			if current != 0 || next != 0 {
-				next, current = current+next, next
-			} else {
-				next = 1
-			}
-			curr := current
-			f.Iterator <- &curr
+			c <- a
+			a, b = b, a+b
 			limit--
 		}
 	}()
-	return f
+	return c
 }
 
 func main() {
-	f := newFibonacci(10)
-	for r := range f.Iterator {
-		fmt.Println(*r)
+	for r := range fibonacci(20) {
+		fmt.Printf("%v ", r)
 	}
 }

combination/fibonacci.go

@@ -0,0 +1,40 @@
+package main
+
+import "fmt"
+
+type fibonacciChan chan int
+
+func (f fibonacciChan) Next() *int {
+	c, ok := <-f
+	if !ok {
+		return nil
+	}
+	return &c
+}
+
+func fibonacci(limit int) fibonacciChan {
+	c := make(chan int)
+	a := 0
+	b := 1
+	go func() {
+		for {
+			if limit == 0 {
+				close(c)
+				return
+			}
+			c <- a
+			a, b = b, a+b
+			limit--
+		}
+	}()
+	return c
+}
+
+func main() {
+	f := fibonacci(20)
+	fmt.Printf("%v ", *f.Next())
+	fmt.Printf("%v ", *f.Next())
+	for r := range f {
+		fmt.Printf("%v ", r)
+	}
+}

base-limit/fibonacci.go → native-approach-limit/native-approach-limit.go

@@ -3,29 +3,26 @@ package main
 import "fmt"
 
 type fibonacci struct {
-	current, next, limit int
+	a, b, limit int
 }
 
 func (f *fibonacci) Next() *int {
 	if f.limit == 0 {
 		return nil
 	}
-	if f.current != 0 || f.next != 0 {
-		f.next, f.current = f.current+f.next, f.next
-	} else {
-		f.next = 1
-	}
+	r := f.a
+	f.a, f.b = f.b, f.a+f.b
 	f.limit--
-	return &f.current
+	return &r
 }
 
 func main() {
-	f := &fibonacci{limit: 10}
+	f := fibonacci{0, 1, 20}
 	for {
 		r := f.Next()
 		if r == nil {
 			return
 		}
-		fmt.Println(*r)
+		fmt.Printf("%v ", *r)
 	}
 }

native-approach/native-approach.go

@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+type fibonacci struct {
+	a, b int
+}
+
+func (f *fibonacci) Next() int {
+	r := f.a
+	f.a, f.b = f.b, f.a+f.b
+	return r
+}
+
+func main() {
+	f := fibonacci{0, 1}
+	for i := 0; i < 20; i++ {
+		fmt.Printf("%v ", f.Next())
+	}
+}