go中斐波切纳数列

package main

import (
	"fmt"
	"runtime"
	// "time"
)

func main() {
	runtime.GOMAXPROCS(1)

	fmt.Println(sum(5))
	fmt.Println(amount(5))
	fmt.Println(addAll(5))
	fmt.Println(addNumbers(10))
	fmt.Println(addNumbers2(10))
	fmt.Println(sort([]int{1, 9, 5, 7, 13, 69, 4, 7, 2, 54, 9, 12, 69}))
}

// 1,1,2,3,5
func sum(n int) int {
	if n == 1 || n == 2 {
		return 1
	}
	return sum(n-1) + sum(n-2)
}

// 1,1,2,3,5
// 性能更佳
func amount(n int) int {
	if n == 1 || n == 2 {
		return 1
	}
	a, b := 1, 1
	for i := 3; i < n; i++ {
		a, b = b, a+b
	}
	return a + b
}

// 1+2+3+4+5
func addAll(n int) int {
	var m int = 0
	for i := 1; i <= n; i++ {
		m += i
	}
	return m
}

// 1+1+2+3+5+8+13
func addNumbers(n int) int {
	a, b := 1, 1
	slice := []int{1, 1}
	sum := 0
	for i := 3; i <= n; i++ {
		a, b = b, a+b
		slice = append(slice, b)
	}
	for _, v := range slice {
		sum += v
	}
	return sum
}

// 1+1+2+3+5+8+13
func addNumbers2(n int) int {
	a, b := 1, 1
	sum := a + b
	for i := 3; i <= n; i++ {
		a, b = b, a+b
		sum += b
	}
	return sum
}

// 冒泡排序
func sort(arr []int) []int {
	for i := 0; i < len(arr)-1; i++ {
		for k := i + 1; k < len(arr); k++ {
			if arr[i] > arr[k] {
				arr[i], arr[k] = arr[k], arr[i]
			}
		}
	}
	return arr
}







第二种方法性能更好！