如果我有一个数组，其中包含的项目，例如：

If I have one array that contains items , for example

["To","Ti","Ta"]

我想有返回数组中追加项目的所有排列功能，在此功能将返回：

I would like to have a function that return all permutations of appended items in array, here function would return:

[["ToTiTa"]["ToTaTi"]["TiToTa"]["TiTaTo"]["TaToTi"]["TaTiTo"]]

你能帮助我吗？

Could you help me please?

推荐答案

你在寻找什么是置换。您可以用递归函数来创​​建它们。

What you are looking for are permutations. You can create them with a recursive function.

下面的code是一个例子。 置换是前端功能，您的code应该调用。 permute_rec 是递归函数，建立置换阵列和交换仅仅是一个方便的功能，在数组交换的元素：

The code below is an example. permute is the front-end function, which your code should call. permute_rec is the recursive function that builds the permutation array and swap is just a convenience function for swapping elements in an array:

function swap(array, i, j) {
    if (i != j) {
        var swap = array[i];
        array[i] = array[j];
        array[j] = swap;
    }
}

function permute_rec(res, str, array) {
    if (array.length == 0) {
        res.push(str);
    } else {
        for (var i = 0; i < array.length; i++) {
            swap(array, 0, i);
            permute_rec(res, str + array[0], array.slice(1));
            swap(array, 0, i);
        }
    }
}

function permute(array) {
    var res = [];

    permute_rec(res, "", array);
    return res;
}

console.log(permute(["A", "B", "C"]));

修改：您可以扩展此code包括子阵与此code的排列：

Edit: You can extend this code to include permutations of subarrays with this code:

function xpermute_rec(res, sub, array) {
    if (array.length == 0) {
        if (sub.length > 0) permute_rec(res, "", sub);
    } else {
        xpermute_rec(res, sub, array.slice(1));
        xpermute_rec(res, sub.concat(array[0]), array.slice(1));
    }
}

function xpermute(array) {
    var res = [];

    xpermute_rec(res, [], array);
    return res;
}

console.log(xpermute(["A", "B", "C"]));

这code创建的所有子阵列，然后使用原来的code创建的排列。 （空数组的情况下被忽略。）

This code creates all subarrays and then uses the original code to create the permutations. (The case of the empty array is skipped.)