## 题目

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 | 1. "123" |

Given *n* and *k*, return the k^th permutation sequence.

**Note:**

- Given
*n*will be between 1 and 9 inclusive. - Given
*k*will be between 1 and n! inclusive.

Example 1:

1 | Input: n = 3, k = 3 |

Example 2:

1 | Input: n = 4, k = 9 |

## 思路

permutations.

## 代码

1 | class Solution(object): |