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:

1const str = "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!)

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

xxxxxxxxxx

      "assert.deepEqual(permutations('rand'), [ 'rand', 'radn', 'rnad', 'rnda', 'rdan', 'rdna', 'arnd', 'ardn', 'anrd', 'andr', 'adrn', 'adnr', 'nrad', 'nrda', 'nard', 'nadr', 'ndra', 'ndar', 'dran', 'drna', 'darn', 'danr', 'dnra', 'dnar' ])"

var assert = require('assert');

​

function permutations(str) {

  // Fill in this method

  return str;

}

​

console.log(permutations('abc'));

​

try {

  assert.deepEqual(permutations('abc'), [

    'abc',

    'acb',

    'bac',

    'bca',

    'cab',

    'cba',

  ]);

​

  console.log(

    'PASSED: ' +

      "assert.deepEqual(permutations('abc'), ['abc', 'acb', 'bac', 'bca', 'cab', 'cba'])"

  );

} catch (err) {

  console.log(err);

}

​

try {

  assert.deepEqual(permutations('a'), ['a']);

Here's a video of us explaining the solution.

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Here's our guided, illustrated walk-through.

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