1 class Solution {
2 public:
3 string getPermutation(int n, int k) {
4 // IMPORTANT: Please reset any member data you declared, as
5 // the same Solution instance will be reused for each test case.
6 string rlt="";
7 unsigned *facts = new unsigned[n+1];
8 unsigned * arr = new unsigned[n];
9 facts[0] = 1;
10 for (int i=1; i<=n; i++){
11 facts[i] = facts[i-1] * i;
12 arr[i-1] = i;
13 }
14 k = k-1;
15 for (int i=1; i<n; i++){
16 int offset = k/facts[n-i];
17 int tmp = arr[i-1+offset];
18 for (int j=i-1+offset; j>=i; j--){
19 arr[j] = arr[j-1];
20 }
21 arr[i-1] = tmp;
22 k = k % facts[n-i];
23 }
24 for (int i=0; i<n; i++)
25 rlt = rlt + (char)('0'+arr[i]);
26 delete []arr;
27 delete []facts;
28 return rlt;
29 }
30 };
