## The challenge#

Write `function MaxRot(n)` which given a positive integer `n` returns the maximum number you got doing rotations similar to the above example.

So `MaxRot` is such as:

• `MaxRot(56789) should return 68957`
• `MaxRot(38458215) should return 85821534`

Examples:

Take a number: `56789`. Rotate left, you get `67895`.

Keep the first digit in place and rotate left the other digits: `68957`.

Keep the first two digits in place and rotate the other ones: `68579`.

Keep the first three digits and rotate left the rest: `68597`. Now it is over since keeping the first four it remains only one digit which rotated is itself.

You have the following sequence of numbers:

`56789 -> 67895 -> 68957 -> 68579 -> 68597`

..and you must return the greatest: `68957`.

## The solution in Golang#

Option 1:

``````package solution
import "strconv"
func MaxRot(n int64) int64 {
str := strconv.FormatInt(n, 10)
max := n
for i := 0; i<len(str)-1 ; i++ {
str = str[:i]+str[i+1:]+string(str[i])
num, _:= strconv.ParseInt(str, 10, 64)
if max < num { max = num }
}
return max
}
``````

Option 2:

``````package solution
import . "strconv"
func MaxRot(n int64) int64 {
s, max := FormatInt(n,10), n
for i := 0; i < len(s); i++ {
s = s[:i] + s[i:][1:] + s[i:][:1]
v,_ := ParseInt(s,10,64)
if max < v {
max = v
}
}
return max
}
``````

Option 3:

``````package solution
import "strconv"
func MaxRot(rot int64) int64 {
rotRunes := []rune(strconv.FormatInt(rot, 10))
for index := 0; index < len(rotRunes) - 1; index++ {
rightPart := append(rotRunes[index + 1:], rotRunes[index])
rotRunes = append(rotRunes[:index], rightPart...)
rotVariation, err := strconv.ParseInt(string(rotRunes), 10, 64)
if err == nil && rotVariation > rot {
rot = rotVariation
}
}
return rot
}
``````

## Test cases to validate our solution#

``````package solution_test
import (
. "github.com/onsi/ginkgo"
. "github.com/onsi/gomega"
)
func dotest(n int64, exp int64) {
var ans = MaxRot(n)
Expect(ans).To(Equal(exp))
}
var _ = Describe("Tests MaxRot", func() {
It("should handle basic cases", func() {
dotest(38458215, 85821534)
dotest(195881031, 988103115)
dotest(896219342, 962193428)
})
})
``````