Good afternoon! Here's our prompt for today.

Write an algorithm that takes an input string like "abc", and prints out all possible permutations of the string. A permutation of a group of elements is defined as one of the n! number possible arrangements the elements can take, where n is the number of elements in the range.

We'd expect the following to hold true, note the permutations printed out:

1str := "abc"
2permutations(str)
3// abc
4// acb
5// bac
6// bca
7// cba
8// cab

A hint here: break the problem down, and think about what steps are going to be repeated. How would we get from "abc" to "acb"?

Constraints

• The string will only consist of lowercase letters
• Length of the string <= 7
• Expected time complexity : O(n*n!)
• Expected space complexity : O(n*n!)

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​

package main

​

import (

  "fmt"

  "reflect"

)

​

func permutations(str string) []string {

  // fill in this function

  return []string{}

}

​

func main() {

  str := "cat"

  fmt.Println(permutations(str))

​

  // test cases start

  fmt.Printf("============================================================\n")

  passed := true

  if reflect.DeepEqual(permutations("abc"), []string{"cba", "bca", "bac", "cab", "acb", "abc"}) == true {

    fmt.Println("TEST 1 --- PASSED")

  } else {

    fmt.Println("TEST 1 --- FAILED : got ", permutations("abc"), " expected ['abc', 'acb', 'bac', 'bca', 'cab', 'cba']")

    passed = false

  }

  if reflect.DeepEqual(permutations("a"), []string{"a"}) == true {

    fmt.Println("TEST 2 --- PASSED")

  } else {

    fmt.Println("TEST 2 --- FAILED : got ", permutations("a"), " expected ['a']")

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