tetsuok/fibonacci_closure.go

stoptime · 2020-01-15T16:26:50Z

@webberwuuu tx for the heads up. After looking at this again I don't think any conditionals are necessary - I've updated my solution.

olehcambel · 2020-04-17T19:00:36Z

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func(int) int {
	return func(n int) int {
		prev, next := -1, 1

		// <=
		for i := 0; i < n; i++ {
			prev, next = next, prev+next
		}

		// return next
		return prev + next
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f(i))
	}
}

pokgopun · 2020-05-04T18:48:26Z

Hate the growing slice but just trying to use it to represent the math fibonacci numbers

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.

func fibonacci() func() int {
	var f,n int // Fn and n
	s := []int{} // The sequence
	return func() int {
		if n > 1 { // Fn = Fn-1 + Fn-2
			f = s[n-1] + s[n-2]
		} else { // F0 = 0, F1 = 1
			f = n
		}
		s = append(s,f) // Add Fn to the sequence
		n++
		return f
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

0
1
1
2
3
5
8
13
21
34

pokgopun · 2020-05-04T20:16:12Z

Hate the growing slice but just trying to use it to represent the math fibonacci numbers

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.

func fibonacci() func() int {
	var f,n int // Fn and n
	s := []int{} // The sequence
	return func() int {
		if n > 1 { // Fn = Fn-1 + Fn-2
			f = s[n-1] + s[n-2]
		} else { // F0 = 0, F1 = 1
			f = n
		}
		s = append(s,f) // Add Fn to the sequence
		n++
		return f
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

0
1
1
2
3
5
8
13
21
34

Here is a much shorter version using a shifting slice to calculate the number instead of the growing slice with verbose if conditions:

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.

func fibonacci() func() int {
	s := []int{0,1}
	return func() int {
		f := s[0]	
		s = s[1:]		
		s = append(s,s[0]+f)
		return f
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

0
1
1
2
3
5
8
13
21
34

saidamir98 · 2020-07-06T07:40:38Z

Fibonacci closure is more fun than I thought!

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	a1 := 0
	a2 := 1
	return func() int {
		f := a1
		a1, a2 = a2, a2+f
		return f
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

HassanYA · 2020-10-29T19:19:35Z

@toolchainx @stvr
Impressive! very much impressed

ranvit · 2021-01-03T00:43:49Z

solution 1 using naked returns

func fibonacci() func() int {
	first, second := 0, 1
	return func() (ret int) {
		ret, first, second = first, second, first+second
		return
	}
}

solution 2 using defer, circumventing the need for a third ret variable

func fibonacci() func() int {
	first, second := 0, 1
	return func() int {
		defer func() { first, second = second, first+second }()
		return first
	}
}

albertleng · 2021-01-09T05:34:21Z

Zero-based:

func fibonacci() func() int {
    fib1 := 0
	fib2 := 1
	return func() int {
		fib1, fib2 = fib2, fib1+fib2
		return fib2-fib1
	}
}

One-based:

func fibonacci() func() int {
    fib1 := 0
	fib2 := 1
	return func() int {
		fib1, fib2 = fib2, fib1+fib2
		return fib2
	}
}

hefedev · 2021-03-08T12:42:21Z

I used growing slice as well but clearly there are better answers here

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
    seq := 0
    var f []int
    
    return func() int {
        switch seq {
            case 0,1:
            f = append(f, seq)
            default:
            f = append(f, f[seq-2]+f[seq-1])
        }
        seq++
        return f[len(f)-1]
    }
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

Worthy-Programmer · 2021-04-20T14:21:09Z

func fibonacci() func() int {
	prev := -1
	now := 1

	return func() int {
		now +=  prev
		prev = now - prev
		return now
	}
}

aibeksarsembayev · 2021-05-16T07:25:59Z

`package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int

func fibonacci() func(int) int {
sum := 0
sum1 := 0
sum2 := 1
return func(x int) int {
if x == 0 {
return sum1
} else if x == 1 {
return sum2
} else {
sum = sum1 + sum2
sum1 = sum2
sum2 = sum
return sum
}
}
}

func main() {
f := fibonacci()
for i := 0; i < 10; i++ {
fmt.Println(f(i))
}
}`

gmac · 2021-10-05T15:31:15Z

Feels succinct:

func fibonacci() func() int {
  var a, b int = 1, 0
  return func() int {
    a, b = b, a + b
    return a
  }
}

bhuppal · 2021-10-29T14:15:52Z

Wired & fun solution

package main

import "fmt"

func fib() func(int) int {
a := 0
b := 1
return func(count int) int {
for ; count > 0; count-- {
a, b = b, a+b
}
return a
}
}

func main () {
fibCalc := fib()
fmt.Println(fibCalc(10))
}

chingizof · 2022-02-12T22:06:25Z

func fibonacci() func() int {
    num, back, n := 0, 1, 0
	  return func () int {
		  if n++; n == 1 {
			  return 0
		  }
		  num, back = num+back, num
		  return num
	  }
}

ydzh · 2022-03-23T15:57:55Z

func fibonacci() func() int {
	first := -1
	second := 1
	return func() int {
		first, second = second, first + second
		return second
	}
}

nerewarin · 2022-05-02T22:54:43Z

func fibonacci() func() int {
	i := -1
	var fib func(i int) int
	
	fib = func(x int) int {
		switch x {
			case 0:
				return 0
			case 1:
				return 1
			default:
				return fib(x-1) + fib(x-2)
		}
	}
	
	fib2 := func() int {
		i++
		return fib(i)
	}
	return fib2
}

NanmiCoder · 2022-05-15T17:53:22Z

func fibonacci() func() int {
	a, b := 0, 1
	fib := func() int {
		var result int
		if a == 0 {
			result = 0
		} else {
			result = b
		}
		a, b = b, a+b
		return result
	}
	return fib
}

niyazz · 2022-05-16T13:00:32Z

func fibonacci() func() int {
	array := [2]int {-1, 1}
	return func() int{
		res := array[0] + array[1]
		array[0] = array[1]
		array[1] = res
		return res
	}
}

QuanTT0110 · 2022-08-19T02:30:48Z

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	
	first, second := 0, 1
	
	return (func () int {
		first, second = second, first + second
		return second
		
	})

}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

anybody can explain for me about this line "first, second = second, first + second" ? please, i don't understand

oboff · 2022-11-11T01:30:57Z

func fibonacci() func() int {
	a,b,c := 0, 0, 1
	return func() int {
		a = b
		b, c = c, b+c
		return a
	}
}

oboff · 2022-11-11T06:54:12Z

@QuanTT0110
similar to writing:

first = second
second = first + second

hktrib · 2023-07-13T00:51:11Z

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	
	first, second := 0, 1
	
	return (func () int {
		first, second = second, first + second
		return second
		
	})

}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

anybody can explain for me about this line "first, second = second, first + second" ? please, i don't understand

I think you need to create a copy. Remember you are using a accumulating reference in first and second. Also think about your logic one more time

guru-das-s · 2023-09-15T17:52:19Z

I solved this using a defer function:

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
	var a, b int = 0, 1

	return func() int {
		update_fn := func() {
			a, b = b, b+a
		}
		defer update_fn()
		return a
	}
}

func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f())
	}
}

vallekaz · 2024-10-27T20:44:25Z

package main

import "fmt"


// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func(int) int {
	return func(x int) int {
		 
		switch x {
		case 0:
			return 0
		case 1:
			return 1
		default:
			return fibonacci()(x-1) + fibonacci()(x-2)
		}
	}

}


func main() {

	f := fibonacci()
	for i := 0; i < 10; i++ {
		fmt.Println(f(i))
	}
}

DAP server listening at: 127.0.0.1:65035
0
1
1
2
3
5
8
13
21
34
Process 36798 has exited with status 0

tetsuok/fibonacci_closure.go

stoptime commented Jan 15, 2020

olehcambel commented Apr 17, 2020

pokgopun commented May 4, 2020 •

edited

Loading

pokgopun commented May 4, 2020 •

edited

Loading

saidamir98 commented Jul 6, 2020 •

edited

Loading

HassanYA commented Oct 29, 2020

ranvit commented Jan 3, 2021 •

edited

Loading

albertleng commented Jan 9, 2021

hefedev commented Mar 8, 2021

Worthy-Programmer commented Apr 20, 2021

aibeksarsembayev commented May 16, 2021 •

edited

Loading

gmac commented Oct 5, 2021 •

edited

Loading

bhuppal commented Oct 29, 2021 •

edited

Loading

chingizof commented Feb 12, 2022 •

edited

Loading

ydzh commented Mar 23, 2022 •

edited

Loading

nerewarin commented May 2, 2022 •

edited

Loading

NanmiCoder commented May 15, 2022

niyazz commented May 16, 2022

QuanTT0110 commented Aug 19, 2022

oboff commented Nov 11, 2022 •

edited

Loading

oboff commented Nov 11, 2022 •

edited

Loading

hktrib commented Jul 13, 2023

guru-das-s commented Sep 15, 2023 •

edited

Loading

vallekaz commented Oct 27, 2024

	package main

	import "fmt"

	// Very naive answer.
	// fibonacci is a function that returns
	// a function that returns an int.
	func fibonacci() func() int {
	n := 0
	a := 0
	b := 1
	c := a + b
	return func() int {
	var ret int
	switch {
	case n == 0:
	n++
	ret = 0
	case n == 1:
	n++
	ret = 1
	default:
	ret = c
	a = b
	b = c
	c = a + b
	}
	return ret
	}
	}

	func main() {
	f := fibonacci()
	for i := 0; i < 10; i++ {
	fmt.Println(f())
	}
	}

tetsuok/fibonacci_closure.go

stoptime commented Jan 15, 2020

olehcambel commented Apr 17, 2020

pokgopun commented May 4, 2020 • edited Loading

pokgopun commented May 4, 2020 • edited Loading

saidamir98 commented Jul 6, 2020 • edited Loading

HassanYA commented Oct 29, 2020

ranvit commented Jan 3, 2021 • edited Loading

albertleng commented Jan 9, 2021

hefedev commented Mar 8, 2021

Worthy-Programmer commented Apr 20, 2021

aibeksarsembayev commented May 16, 2021 • edited Loading

gmac commented Oct 5, 2021 • edited Loading

bhuppal commented Oct 29, 2021 • edited Loading

chingizof commented Feb 12, 2022 • edited Loading

ydzh commented Mar 23, 2022 • edited Loading

nerewarin commented May 2, 2022 • edited Loading

NanmiCoder commented May 15, 2022

niyazz commented May 16, 2022

QuanTT0110 commented Aug 19, 2022

oboff commented Nov 11, 2022 • edited Loading

oboff commented Nov 11, 2022 • edited Loading

hktrib commented Jul 13, 2023

guru-das-s commented Sep 15, 2023 • edited Loading

vallekaz commented Oct 27, 2024

pokgopun commented May 4, 2020 •

edited

Loading

pokgopun commented May 4, 2020 •

edited

Loading

saidamir98 commented Jul 6, 2020 •

edited

Loading

ranvit commented Jan 3, 2021 •

edited

Loading

aibeksarsembayev commented May 16, 2021 •

edited

Loading

gmac commented Oct 5, 2021 •

edited

Loading

bhuppal commented Oct 29, 2021 •

edited

Loading

chingizof commented Feb 12, 2022 •

edited

Loading

ydzh commented Mar 23, 2022 •

edited

Loading

nerewarin commented May 2, 2022 •

edited

Loading

oboff commented Nov 11, 2022 •

edited

Loading

oboff commented Nov 11, 2022 •

edited

Loading

guru-das-s commented Sep 15, 2023 •

edited

Loading