/*
package main

import "fmt"

func main() {
	// 指向 int 类型的 指针类型.
	var p *int

	i, j := 42, 2701

	p = &i
	fmt.Println(*p)

	*p = 21
	fmt.Println(i)

	p = &j
	*p = *p / 37
	fmt.Println(j)

}
*/

/*
package main

import "fmt"

type Vertex struct {
	X int
	Y int
}

func main() {
	//fmt.Println(Vertex{1, 2})

	v := Vertex{1, 2}
	fmt.Println(v.X)

	v.X = 4
	fmt.Println(v)
}
*/

/*
package main

import "fmt"

type Vertex struct {
	X int
	Y int
}

func main() {
	v := Vertex{1, 2}
	p := &v

	p.X = 1e9
	fmt.Println(v)
}
*/

/*
package main

import "fmt"

type Vertex struct {
	X, Y int
}

var (
	v1 = Vertex{1, 2}
	v2 = Vertex{X: 1}
	v3 = Vertex{}
	p  = &Vertex{1, 2}
)

func main() {
	fmt.Println(v1, p, v2, v3)
}
*/

/*
package main

import "fmt"

func main() {
	var a [2]string
	a[0] = "Hello"
	a[1] = "world"
	fmt.Println(a)
}
*/

/*
package main

import "fmt"

func main() {
	p := []int{2, 3, 5, 7, 11, 13}
	fmt.Println("p ==", p)

	for i := 0; i < len(p); i++ {
		fmt.Printf("p[%d] == %d\n", i, p[i])
	}
}
*/

/*
package main

import "fmt"

func main() {
	p := []int{2, 3, 5, 7, 11, 13}
	fmt.Println("p ==", p)
	fmt.Println("p[1:4] =", p[1:4])

	fmt.Println("p[:3] =", p[:3])
	fmt.Println("p[4:] =", p[4:])
}
*/

/*
package main

import "fmt"

func printSlice(s string, x []int) {
	fmt.Printf("%s len=%d cap=%d %v\n",
		s, len(x), cap(x), x)
}

func main() {
	a := make([]int, 5)
	printSlice("a", a)

	b := make([]int, 0, 5)
	printSlice("b", b)

	c := b[:2]
	printSlice("c", c)

	d := c[2:5]
	printSlice("d", d)
}
*/

/*
package main

import "fmt"

func main() {
	var z []int
	fmt.Println(z, len(z), cap(z))

	if z == nil {
		fmt.Println("nil!")
	}
}
*/

/*
package main

import "fmt"

func printSlice(s string, x []int) {
	fmt.Printf("%s len=%d cap=%d %v\n",
		s, len(x), cap(x), x)
}

func main() {
	var a []int
	printSlice("a", a)

	a = append(a, 0)
	printSlice("a", a)

	a = append(a, 1)
	printSlice("a", a)

	a = append(a, 2, 3, 4)
	printSlice("a", a)
}
*/

/*
package main

import "fmt"

var pow = []int{1, 2, 4, 8, 16, 32, 64, 128}

func main() {
	for i, v := range pow {
		fmt.Printf("2**%d = %d\n", i, v)
	}
}
*/

/*
package main

import "fmt"

func main() {
	pow := make([]int, 10)

	for i := range pow {
		pow[i] = 1 << uint(i)
	}
	fmt.Println(pow)

	for _, value := range pow {
		fmt.Printf("%d\n", value)
	}
}
*/

/*
package main

import "fmt"

type Vertex struct {
	Lat, Long float64
}

var m map[string]Vertex

func main() {
	fmt.Println(m)

	m = make(map[string]Vertex)
	m["Bell Labs"] = Vertex{
		40.68433, -74.39967,
	}
	fmt.Println(m["Bell Labs"])
}
*/

/*
package main

import "fmt"

type Vertex struct {
	Lat, Long float64
}

var m = map[string]Vertex{
	"Bell Labs": Vertex{
		40.68433, -74.39967,
	},
	"Google": Vertex{
		37.42202, -122.08408,
	},
}

func main() {
	fmt.Println(m)
}
*/

/*
package main

import "fmt"

type Vertex struct {
	Lat, Long float64
}

var m = map[string]Vertex{
	"Bell Labs": {40.68433, -74.39967},
	"Google":    {37.42202, -122.08408},
}

func main() {
	fmt.Println(m)
}
*/

/*
package main

import "fmt"

func main() {
	m := make(map[string]int)

	m["Answer"] = 42
	fmt.Println("The value:", m["Answer"])

	m["Answer"] = 48
	fmt.Println("The value:", m["Answer"])

	delete(m, "Answer")
	fmt.Println("The value:", m["Answer"])

	v, ok := m["Answer"]
	fmt.Println("The value:", v, "Present?", ok)
}
*/

/*
package main

import (
	"fmt"
	"math"
)

func main() {
	hypot := func(x, y float64) float64 {
		return math.Sqrt(x*x + y*y)
	}

	fmt.Println(hypot(3, 4))
}
*/

/*
package main

import "fmt"

func adder() func(int) int {
	sum := 0
	return func(x int) int {
		sum += x
		return sum
	}
}

func main() {
	pos, neg := adder(), adder()
	for i := 0; i < 10; i++ {
		fmt.Println(
			pos(i),
			neg(-2*i),
		)
	}
}
*/

package main

import "fmt"

// 斐波那契数列实现
func fibonacci() func() []int {
	var result []int
	return func() []int {
		size := len(result)

		if size <= 1 {
			result = append(result, 1)
		} else {
			result = append(result, result[size-2]+result[size-1])
		}

		return result
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 20; i++ {
		fmt.Println(f())
	}
}