Golang recursion question :

gistfile1.txt

Find the factorial of number using recusion in Golang : 
Find the sum of natural number using recursion in Golang :
Find the reverse of string using recursion in Golang :
Program to check prime number using recursion in Golang :
Program to print fibonacci series nth term :
Program to generate permuation of string :
Program to find GCD of a numbers :
Program to find the N th term of fibonacci number using memoization :
Program to find the subset of a set :
Program to find the Tower of Hanoi problem : 

// Online Go compiler to run Golang program online
// Print "Try programiz.pro" message

package main
import "fmt"

//factorial of a number
func fact(n int) int{
if n==0 {
return 1
}
return n*fact(n-1)
}
//natural number sum
func sum(n int) int {
if n==0 {
return 0
}
return n+sum(n-1)
}
//reverse of a string
func reverse(s string)string {
if len(s) == 0 {
return s
}
return string(s[len(s)-1])+reverse(s[:len(s)-1])
}

//prime number problem
func isPrime(n , i int) bool {
if i*i > n {
return true
}
if n%i == 0 {
return false
}
return isPrime(n, i+1)
}

func checkPrime(n int) bool {
if n<=1 {
return false
}
return isPrime(n,2)
}

// fibonacci series
func fib(n int )int {
if n<=1 {
return n
}
return fib(n-1)+fib(n-2)
}
//generate permutation of a string
func permute(s string)[]string{
var result []string
permuteHelper(s,"",&result)
return result
}
func permuteHelper(s,current string, result *[]string){
if len(s)== 0 {
*result = append(*result, current)
return
}
for i:=0; i<len(s); i++{
newStr := s[:i] +s[i+1:]
permuteHelper(newStr, current+string(s[i]),result)

}

}
// gcd of numbers
func gcd(a,b int) int{
if b==0 {
return a
}
return gcd(b,a%b)
}
//solve Nth fibonacci number using memoization
func fibonacci(n int , memo map[int]int) int {
if n<=1 {
return n
}
if _, found := memo[n]; found {
return memo[n]
}
memo[n]=fibonacci(n-1,memo)+fibonacci(n-2,memo)
return memo[n]
}

func main() {
fmt.Println("factorial of number =",fact(5))
fmt.Println("Sum of number=",sum(5))
fmt.Println("Reverse of string=",reverse("Hello"))
fmt.Println("Check number 11 is prime =",checkPrime(11))
fmt.Println("Fibonacci series is :",fib(5))
fmt.Println("GCD of number 28 and 35 is =",gcd(28,35))
fmt.Println("Permutation of string abc=",permute("abc"))
memo:=make(map[int]int)
fmt.Println("Nth term of fibnaocci:",fibonacci(10,memo))
}