leetcode

0 class Solution {

1 public:

2 vector<int> circularPermutation(int n, int start) {

3 vector<int> res = {0, 1};

4 int idx = 2;

5 for (int i = 1; i < n; i++) {

6 const int size = 1 << i;

7 for (int j = 1; j <= size; j++) {

8 res.push_back(size | res[size - j]);

9 if (res.back() == start) idx = res.size();

10 }

11 }

12 if (start == 0) return res;

13 reverse(begin(res), begin(res) + idx);

14 reverse(begin(res) + idx, end(res));

15 return res;

16 }

17 };

18

19 class Solution {

20 public:

21 vector<int> circularPermutation(int n, int start) {

22 vector<int> res;

23 for (int i = 0; i < (1 << n); i++)

24 res.push_back(start ^ i ^ (i >> 1));

25 return res;

26 }

27 };