math.big 用于大整数计算

https://www.cnblogs.com/welhzh/p/8981096.html

1, math/big

package main

import (
	"fmt"
	"math/big"
	"time"
)

const LIM = 10000 //求第10000位的费布拉切数

var fibs [LIM]*big.Int //使用数组保存计算出来的费布拉切数的指针

func main() {
	result := big.NewInt(0)
	start := time.Now()
	for i := 0; i < LIM; i++ {
		result = fibonacci(i)
		if i == LIM-1 {
			fmt.Printf("fibonacci(%d) is: %d\n", i, result)
		}
	}

	fmt.Println(result)
	fmt.Printf("%T\n", result)
	end := time.Now()
	delta := end.Sub(start)
	fmt.Printf("longCalculation took this amount of time: %s\n", delta)
}

func fibonacci(n int) (res *big.Int) {
	if n <= 1 {
		res = big.NewInt(1)
	} else {
		temp := new(big.Int)
		res = temp.Add(fibs[n-1], fibs[n-2])
	}
	fibs[n] = res
	return
}

2, math/big

package main

import (
	"fmt"
	"math/big"
)

func genFibLst(n int) (a []string) {
	n1 := big.NewInt(1)
	n2 := big.NewInt(1)
	fmt.Printf("n1=%d,type(n1)=%T n2=%d,type(n2)=%T\n",n1,n1,n2,n2)
	fmt.Printf("n1=%s, n2=%s, n1.string=%s\n",n1,n2,n1.String())
	fmt.Printf("n1=%#v, n1=%v \n",n1,n1)
	fmt.Printf("n1=%#v, n1=%v %v \n",n1,n1,*n1)
	fmt.Printf("n2=%#v, n2=%v %v\n",n1,n1,*n2)
	for n > 0 {
		a = append(a, n1.String())
		tmp := n1.Add(n1, n2)
		fmt.Printf("----------n1=%s, n2=%s, a=%v,tmp=%s \n",n1,n2,a,tmp)
		n1 = n2
		n2 = tmp
		n --
	}
	return a
}

func main() {
	lst := genFibLst(10)
	for index, val := range lst {
		fmt.Println(">>>",index + 1, val)
	}
}