1// Shuffle function implementation - fill in your code!
2function shuffle(arr) {
3   for (let i = 0; i < arr.length; i++) {
4     const j = i + Math.floor(Math.random() * (arr.length - i));
5     [arr[i], arr[j]] = [arr[j], arr[i]];
6  }
7}
8
9const arr = [1, 2, 3, 4];
10const permutations = [
11  [1, 2, 3, 4], [1, 2, 4, 3], [1, 3, 2, 4], [1, 3, 4, 2], [1, 4, 2, 3], [1, 4, 3, 2],
12  [2, 1, 3, 4], [2, 1, 4, 3], [2, 3, 1, 4], [2, 3, 4, 1], [2, 4, 1, 3], [2, 4, 3, 1],
13  [3, 1, 2, 4], [3, 1, 4, 2], [3, 2, 1, 4], [3, 2, 4, 1], [3, 4, 1, 2], [3, 4, 2, 1],
14  [4, 1, 2, 3], [4, 1, 3, 2], [4, 2, 1, 3], [4, 2, 3, 1], [4, 3, 1, 2], [4, 3, 2, 1]
15];
16
17// Shuffle the array
18shuffle(arr);
19
20// Validate the shuffled array
21const isValidPermutation = permutations.some(permutation => JSON.stringify(permutation) === JSON.stringify(arr));
22
23if (isValidPermutation) {
24  console.log('The shuffled array is a valid permutation:', arr);
25} else {
26  console.log('Something went wrong! The shuffled array does not match any of the valid permutations.');
27}