Calcualte Politeness of Number in Golang

// Get all prime factors of a given number n
func PrimeFactors(n int) (pfs []int) {
      // Get the number of 2s that divide n
      for n%2 == 0 {
              pfs = append(pfs, 2)
              n = n / 2
      }

      // n must be odd at this point. so we can skip one element
      // (note i = i + 2)
      for i := 3; i*i <= n; i = i + 2 {
              // while i divides n, append i and divide n
              for n%i == 0 {
                      pfs = append(pfs, i)
                      n = n / i
              }
      }

      // This condition is to handle the case when n is a prime number
      // greater than 2
      if n > 2 {
              pfs = append(pfs, n)
      }

      return
}

// Algorithm from wiki: An easy way of calculating the politeness of a positive
// number is that of decomposing the number into its prime factors, taking the
// powers of all prime factors greater than 2, adding 1 to all of them,
// multiplying the numbers thus obtained with each other and subtracting 1.
func CalculatePoliteness(n int) int {
      pfs := PrimeFactors(n)

      // key: prime
      // value: prime exponent
      m := make(map[int]int)
      for _, prime := range pfs {
              _, ok := m[prime]
              if ok {
                      m[prime] += 1
              } else {
                      m[prime] = 1
              }
      }

      politeness := 1
      for prime, exponent := range m {
              if prime > 2 {
                      politeness *= (exponent + 1)
              }
      }
      politeness -= 1

      return politeness
}

import (
      "testing"
)

func TestCalculatePoliteness(t *testing.T) {
      if CalculatePoliteness(9) != 2 {
              t.Error("politeness of 9 is not 2")
              return
      }
      if CalculatePoliteness(15) != 3 {
              t.Error("politeness of 15 is not 3")
              return
      }
      if CalculatePoliteness(90) != 5 {
              t.Error("politeness of 90 is not 5")
              return
      }
}