leetcode

0 class Solution {

1 public:

2 string getPermutation(int n, int k) {

3 vector<char> avail = {'1', '2', '3', '4', '5', '6', '7', '8', '9'};

4 int factorial = 1, pos;

5 string res;

6 for (int i = 1; i <= n; i++)

7 factorial *= i;

8 for (k--; n; n--) {

9 factorial /= n;

10 res += avail[pos = k / factorial], k -= pos * factorial;

11 for (int i = pos; i < avail.size() - 1; i++)

12 avail[i] = avail[i + 1];

13 }

14 return res;

15 }

16 };