whatinthehell.js

const getRandomInt = (min, max) => {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

const dValues = (() => {
    const result = new Array(27);
    result[0] = 1;
    result[1] = 0;
    for (let i = 2; i < letters.length; i++) {
        result[i] = (i - 1) * (result[i - 1] + result[i - 2]);
    }
    return result;
})();

const swap = (arr, i, j) => {
    const tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
}

const randomDerangement = (arr) => {
    const A = arr.slice();
    const mark = new Array(A.length);
    mark.fill(false);
    let i = A.length - 1;
    let u = A.length - 1;

    while (u >= 2) {
        if (!mark[i]) {
            let j = getRandomInt(0, i - 1);
            while (mark[j]) {
                j = getRandomInt(0, i - 1);
            }
            swap(A, i, j);
            let p = Math.random();
            let uVal = ((u - 1) * dValues[u - 2])/ dValues[u];
            if (p < uVal) {
                mark[j] = true;
                u = u - 1;
            }
            u = u - 1;
        }
        i = i - 1;
    }
    return A;
}