Golang - Printing all possible orders of elements in an array. WARNING: HIGHLY INEFFICIENT, JUST FOR FUN, DON'T USE IN PRODUCTION

print.go

package main

import (
	"fmt"
	"strings"
)

func main() {

	source := []string{
		"One",
		"Two",
		"Three",
		"Four",
		"Five",
		"Six",
	}

	current := make([]string, len(source))
	recursiveCombinationPrinter(source, current, 0)
}

// Prints all possible combinations recursively
// Arguments:
// - source: Source array of elements to pick from
// - current: Array that is filled by method with current combination
// - index: Current depth of recursive function
func recursiveCombinationPrinter(source []string, current []string, index int) {
	// Current combination is ready to be printed, print it
	if index == len(source)+len(current) {
		fmt.Println(strings.Join(current, ", "))
		return
	}

	// Loop through all element, and recursively call self
	// Remove current element from the source for the next call.
	for i := 0; i < len(source); i++ {

		// Use an element
		current[index] = source[i]

		// Remove this element, as it can only occur once.
		newSource := make([]string, len(source))
		copy(newSource, source)
		newSource = removeIndex(newSource, i)

		// Call recursively to determine element for next index
		recursiveCombinationPrinter(newSource, current, index+1)
	}
}

// Very memory inefficient but simple way to do this. Don't in production.
func removeIndex(s []string, index int) []string {
	if len(s) == 0 {
		return s
	}
	return append(s[:index], s[index+1:]...)
}