The set `[1, 2, 3, ..., n]` contains a total of `n!` unique permutations.

By listing and labeling all of the permutations in order, we get the following sequence for `n = 3`:

1. `"123"`
2. `"132"`
3. `"213"`
4. `"231"`
5. `"312"`
6. `"321"`

Given `n` and `k`, return the `kth` permutation sequence.

Example 1:

    Input: n = 3, k = 3
    Output: "213"

Example 2:

    Input: n = 4, k = 9
    Output: "2314"

Example 3:

    Input: n = 3, k = 1
    Output: "123"

Constraints:

- `1 <= n <= 9`
- `1 <= k <= n!`