can you shuffle() an array?

Question

How would you implement a shuffle() ?

When passed with an array, it should modify the array inline to generate a randomly picked permutation at the same probability.

for an array like this:

const arr = [1, 2, 3, 4]

there would be possibly 4! = 24 permutations

[1, 2, 3, 4]
[1, 2, 4, 3]
[1, 3, 2, 4]
[1, 3, 4, 2]
[1, 4, 2, 3]
[1, 4, 3, 2]
[2, 1, 3, 4]
[2, 1, 4, 3]
[2, 3, 1, 4]
[2, 3, 4, 1]
[2, 4, 1, 3]
[2, 4, 3, 1]
[3, 1, 2, 4]
[3, 1, 4, 2]
[3, 2, 1, 4]
[3, 2, 4, 1]
[3, 4, 1, 2]
[3, 4, 2, 1]
[4, 1, 2, 3]
[4, 1, 3, 2]
[4, 2, 1, 3]
[4, 2, 3, 1]
[4, 3, 1, 2]
[4, 3, 2, 1]

your shuffle() should transform the array in one of the above array, at the same 1/24 probability.

notes

Your shuffle() will be called multiple times, to calculate the probability on each possible result, and test again standard deviation

ref: https://javascript.info/task/shuffle

Code

/**
 * @param {any[]} arr
 * @returns {void}
 */
function shuffle(arr) {
  // modify the arr inline to change the order randomly
}

Source

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