Kth Permutation Sequence

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 ) :

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

Given n and k, return the kth permutation sequence.

For example, given n = 3, k = 4, ans = "231"

Good questions to ask the interviewer :

  • What if n is greater than 10. How should multiple digit numbers be represented in string?
    > In this case, just concatenate the number to the answer.
    > so if n = 11, k = 1, ans = "1234567891011"

  • Whats the maximum value of n and k?
    > In this case, k will be a positive integer thats less than INT_MAX.
    > n is reasonable enough to make sure the answer does not bloat up a lot.

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