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 (ie, for n = 3):
“123““132““213““231““312““321“
Given n and k, return the _k_th permutation sequence.
Note: Given n will be between 1 and 9 inclusive.