leetcode

0 class Solution {

1 bool seen[21] = {0};

2 vector<int> res = vector(39, 0);

3

4 bool rec(const int n, int crnt) {

5 while (crnt < size(res) && res[crnt])

6 crnt++;

7 if (crnt == size(res)) return true;

8

9 for (int i = n; i > 1; i--) {

10 if (seen[i] || crnt + i >= size(res) || res[crnt + i]) continue;

11 res[crnt + i] = res[crnt] = i;

12 seen[i] = true;

13 if (rec(n, crnt + 1)) return true;

14 seen[i] = false;

15 res[crnt + i] = 0;

16 }

17

18 if (!seen[1]) {

19 res[crnt] = 1;

20 seen[1] = true;

21 if (rec(n, crnt + 1)) return true;

22 seen[1] = false;

23 }

24 res[crnt] = 0;

25

26 return false;

27 }

28

29 public:

30 vector<int> constructDistancedSequence(const int n) {

31 res.resize(2 * n - 1);

32 rec(n, 0);

33 return res;

34 }

35 };