Prancing Pony (Golang)

prancing_pony.go

package main

import (
  "fmt"
  "time"
  "strings"
)


func palindromeCombinations(dwarf_names []string) <-chan []string {
  name_channel := make(chan []string)
  
  for i, v := range dwarf_names {
    dwarf_names[i] = strings.ToUpper(v)
  }
    
  // Start a go routine on a closure that will add the outputs to the channel
  go func(c chan []string) {
    defer close(c) // close the channel when everything is finished
    AddName(c, []string{}, dwarf_names, len(dwarf_names)) // We start by feeding it an empty string
  }(name_channel)

  return name_channel // Return the channel to the calling function
}

func isPalindrome(name string) bool {
  for i := 0; i < len(name)/2; i++ {
    if name[i] != name[len(name)-i-1] {
      return false
    }
  }
  return true
}

func AddName(name_channel chan []string, combo []string, dwarf_names []string, length int) {
  
  if length <= 0 {
    return
  }
  
  var newCombo []string
  for i, ch := range dwarf_names {
    newCombo = append(combo,ch)
    newd := make([]string, len(dwarf_names)-1)
    copy(newd[:i],dwarf_names[:i])
    copy(newd[i:],dwarf_names[i+1:])
    if isPalindrome(strings.Join(newCombo,"")){
      name_channel <- newCombo  
    }
    AddName(name_channel, newCombo, newd, length-1)
  } 
}


func main() {
  start := time.Now()
  for combinations := range palindromeCombinations([]string{"Gimli", "Fili","Ilif","Ilmig","Mark"}) {
    fmt.Println(combinations)
  }
  elapsed := time.Since(start)
  fmt.Println("")
  fmt.Printf("Running took %s", elapsed) 
  fmt.Println("Done!")
}