参考代码：

def fact(j):
    sum = 0
    if j == 0:
        sum = 1
    else:
        sum = j * fact(j - 1)
    return sum

package main

import (
    "fmt"
)

func fact(j int) int {
    sum := 0
    if j == 0 {
        sum = 1
    } else {
        sum = j * fact(j -1)
    }
    return sum
}

func main() {
    /*
    利用递归方法求 5!
    阶乘 F(n)=F(n-1)*n
    */

    j := 5
    fmt.Println(fact(j))
 }